Outdoor project weather: frequently asked questions

Enter your ZIP code on the home page and you get a Good, Maybe or No for ten outdoor projects across the next 7 days, built from the hourly National Weather Service forecast for your spot. Each project also has its own page with the best time window for every day, for example deck staining or pouring concrete.

Good means every check passes for at least one work window that day. Maybe means the job is doable but something needs watching, such as a 30–49% chance of rain while you work or a cool night after. No means at least one limit is likely to make the job fail, such as a 50% or higher chance of rain during the dry period the project needs, or a freeze on fresh concrete. Each verdict lists the reasons. The methodology page has every rule.

Most weather failures happen while a coating or slab cures, not while you work: rain the night after staining, dew on fresh paint at dusk, a freeze two days after a pour. So each project checks the hours after you finish too, up to 72 hours for concrete. The weather timing guide explains why.

It is the chance that measurable rain (0.01 inch or more) falls at your location in that period, not the share of the day it rains. The forecast treats 30% or more in a period that must stay dry as a caution and 50% or more as likely rain. More in What does a 40% chance of rain mean?

The forecast covers 7 days. The first one to three days are the most reliable, so use days 4–7 to pick a likely day and check again the evening before. How to read an hourly forecast shows what to look at.

Yes, in Canada, the UK, Ireland and most of Europe. Choose your country above the search box and enter a postcode or town, or use your device location. Outside the U.S. the forecast comes from MET Norway, with temperatures in °C. See how the data works.

A DIY Day is a free website that turns the hourly National Weather Service forecast into go/no-go verdicts for outdoor home projects in the U.S. Enter a ZIP code on the home page and each of the next 7 days gets a Good, Maybe or No for ten jobs, with the best time window and the reasons. The complete guide to outdoor project weather explains every rule.

Yes. There is no account, app or subscription. The site is paid for by ads and Amazon affiliate links, and the verdicts are the same whatever is advertised. See the affiliate disclosure and the About page.

A normal weather app shows the forecast. It does not tell you whether that forecast suits stain, paint, concrete or sealer. A project forecast such as A DIY Day checks temperature, humidity, dew point, wind and the rain and cold after you finish for each job. Use it to pick the day and your usual app for radar on the day. The comparison table shows the difference.

Because the problem is usually after you finish: a night below the product’s minimum, dew in the evening, or rain the next morning before the finish has set. Each verdict lists the exact reason and the hour. Why a nice day can still be the wrong day explains it.

Yes. The home page scores all ten projects for each of the next 7 days in one grid, so you can plan, for example, pressure washing on Saturday and staining on Monday after the wood dries. Open a project page, such as deck staining, for the hour-by-hour window.

For most paint, stain, garage epoxy and spray paint, above 85°F calls for shade and above 90°F is too hot. Driveway sealer goes to 95°F, concrete and caulk to 100°F and pressure washing to 105°F. The heat limits table lists every job.

Above 85% is too humid for exterior paint, deck stain, garage epoxy and spray paint, and driveway sealer stops at 90%. Spray paint is best under 65% and paint and epoxy under 75%. See the humidity limits by project.

Keep the surface at least 5°F above the dew point while you work, and avoid dew for several hours after. At 85% humidity the air is only about 5°F above the dew point. The dew point table shows the gap at common temperatures and humidity levels.

Not with most exterior paints, which list a maximum of about 90°F for the air and the surface. On a 95°F day, look for a cooler morning window and paint only in shade. The exterior painting forecast finds the hours under 90°F.

Mid-morning, once the dew has dried and before the hottest hours. Afternoon sun causes lap marks, and evenings bring dew. The summer timing table gives the start times each forecast uses.

Pressure washing, caulking in the shade and early-morning concrete pours handle heat best, while painting, staining and epoxy usually have to wait. The 7-day project grid shows which jobs are still Good each day.

High humidity is helpful once concrete is placed, because the slab loses water more slowly. Low humidity, heat and wind are the risk, since fast evaporation causes plastic shrinkage cracks. The concrete forecast estimates the evaporation rate every hour.

Yes, water-based stains most of all, because they dry by evaporation. In humid weather allow more time before rain or foot traffic. The deck staining forecast allows humidity up to 85% and prefers 48 dry hours after you finish.

The forecast wants the 24 hours before you start to be dry, and after a soaking rain 48 hours of dry, breezy weather is safer. Shaded boards and the undersides dry last. Before you open the can, sprinkle a little water on the boards: if it soaks in within about a minute, the wood is dry enough. Is your deck dry enough to stain? covers the test, and How long after rain can you stain, paint or seal? compares the wait for each job.

The deck stain forecast needs 24 hours with no likely rain after you finish and prefers 48. Water-based stains are often dry to the touch in a few hours in warm weather, while oil-based stains can stay soft for a day or more, especially when it is cool or humid. Your product label gives the exact rain-ready time.

Yes, while the days reach at least 50°F and the nights stay up. The forecast marks a day No if it drops below 40°F within 12 hours of finishing and warns below 50°F. Short days and heavy morning dew are what usually end the season. See How late in the fall can you stain, paint or seal?

The forecast allows up to 90°F and prefers 55–85°F. Deck boards in full sun can run much hotter than the air, which makes stain flash-dry and leave lap marks. On hot days stain early in the morning or in shade, a few boards at a time. Surface vs. air temperature explains the gap.

Evening staining is risky because dew often forms on the wet stain as the air cools. The forecast needs humidity at or below 85%, the air at least 5°F above the dew point, and no dew in the 4 hours after you finish, so its work window starts between 9 AM and 2 PM. Dew point for painting and staining shows how to check it.

In most of the U.S., late May to June and September to early October, when afternoons are mild, humidity is lower and nights stay above 50°F. In the South and Southwest, fall and spring beat summer heat. Region-by-region advice is in the complete outdoor project weather guide.

Water-based stains are often dry to the touch in 1–4 hours in warm, dry weather, and oil-based stains in 4–24 hours. Cool or humid weather can double that. The deck stain forecast wants 24 rain-free hours after you finish, 48 if possible, and your label gives the exact recoat and foot-traffic times.

No. Pressure washing soaks the wood, and stain on wet boards dries blotchy and peels. Give it one to two dry days, then do the water drop test from Is your deck dry enough to stain? The pressure washing forecast helps you pick a wash day with dry days after it.

For standard exterior latex, yes: most need 50°F. Paints labeled for low-temperature use can go on at 35°F, and the temperature has to stay above that minimum while the paint dries, including overnight. The exterior paint forecast marks a day No below 35°F and tells you when only a low-temperature paint will work.

The forecast allows up to 90°F and prefers 50–85°F. In heat, paint dries before it levels, which leaves lap marks and brush marks, and siding in direct sun is hotter still. Follow the shade around the house: paint the west side in the morning and the east side in the afternoon.

No. Fog means the air is at its dew point, so surfaces are wet or close to it, and paint applied then can blister, streak or fail to bond. Wait until the fog lifts and the surface is dry, and the air is at least 5°F above the dew point. That is the rule the forecast uses. See How long exterior paint needs before it rains for what moisture does to fresh paint.

Usually not. Fresh latex paint hit by evening dew can develop sticky, brown or soapy streaks (surfactant leaching). Finish early enough that the paint has a few hours to dry before the air cools toward the dew point. The forecast checks the 4 hours after you finish for dew.

Mid-morning to mid-afternoon, after the dew has dried and early enough for the paint to set before evening dew. The exterior painting forecast looks for a 4-hour window starting between 9 AM and 1 PM. Follow the shade around the house on hot days.

It is best avoided on warm days. Siding in full sun can be much hotter than the air, so paint dries before it levels and leaves lap marks. Paint each side after the sun has moved off it. Surface vs. air temperature explains why.

For standard latex paint, the night should stay at or above 50°F. Low-temperature paints allow 35°F. The painting forecast checks the 8 hours after you finish and marks the day No below 35°F and Maybe below 50°F. More in how late in the fall you can paint.

The concrete forecast needs at least 40°F during the pour, marks a day No if a freeze is forecast within 48 hours, and Maybe if lows drop below 40°F within 72 hours. Concrete has to be protected from freezing until it reaches about 500 psi, which takes about two days for a normal mix in cool weather. Insulated blankets and accelerated mixes extend the season. See Pouring concrete in hot or cold weather.

Avoid it. Rain during placing and finishing adds water to the surface, which weakens it and leads to dusting and scaling. The forecast marks a day No if rain is likely (50% or more) during the pour window. Keep plastic sheeting on site in case a shower arrives early.

Once the surface has set hard enough that rain won’t mark it, usually a few hours in warm weather and longer in cool weather, rain does little harm and can even help curing. The forecast wants 8 dry hours after you finish and prefers 24.

The same limits apply: don’t pour into frozen ground, and keep the concrete above freezing for about two days. Fast-setting post mixes also slow down in the cold. On a cool day, pour in the morning so the concrete gets the warmest hours.

Wind, low humidity and heat pull water off the surface faster than it can rise through the slab, which causes plastic shrinkage cracks. The forecast estimates the evaporation rate every hour and flags anything above 0.2 lb/ft²/hr, the threshold in the American Concrete Institute hot-weather guide. The methodology page shows the formula.

Late spring and early fall in most of the U.S.: mild days, no freeze risk and less evaporation than midsummer. In hot regions pour early in the morning, and in the North watch the 48-hour freeze rule in fall. See pouring concrete in hot or cold weather and the concrete forecast.

Not with a normal mix and no protection. The concrete forecast needs at least 40°F while you pour and no freeze within 48 hours. Professionals pour in colder weather with heated materials, accelerators and insulated blankets, as described in our cold-weather concrete guide.

For a typical mix in mild weather, foot traffic is usually fine after about a day and cars after about a week. Cold weather slows strength gain, so wait longer when nights are cool. Check with your concrete supplier or the bag, and see the concrete rules for the temperatures that slow curing.

Most asphalt sealers need 50°F or higher while you apply them and for the next 24 hours, and the driveway sealing forecast uses exactly that rule. A sunny 55°F afternoon followed by a 38°F night is a No. Cold nights, not cold days, usually end the season. See How late in the fall can you seal?

The pavement must be fully dry, including low spots and cracks where water sits. The forecast checks the 24 hours before you start and warns if rain is expected. After a heavy rain, a full sunny day is usually enough on asphalt. See How long after rain can you stain, paint or seal?

Late spring through early fall, on a sunny day between 60°F and 90°F with no rain for at least 24 hours (ideally 48). Start mid-morning once dew has dried so the sealer gets the afternoon sun: the forecast looks for a 3-hour window starting between 10 AM and 1 PM. The seasonal calendar shows when that window opens where you live.

60–90°F in sun, with at least 50°F during application and for the 24 hours after. Above about 95°F the pavement can be too hot for the sealer to bond. The driveway sealing forecast checks both, and the complete guide explains the 24-hour rule.

It is risky. The sealer loses the afternoon sun it needs to cure, and the cooler night and dew slow it further. The forecast looks for a 3-hour window starting between 10 AM and 1 PM.

Only if the rain is at least 24 hours after you finish, and 48 is safer in cool or humid weather. The forecast marks the day No if rain is likely (50% or more) within 24 hours. What a 40% chance of rain means helps you judge the in-between days.

Only if the product has time to become rainfast first. Labels for common glyphosate weed killers give rainfast times from about 30 minutes to several hours depending on the formula, so read yours. The weed killer forecast looks for 6 dry hours after spraying, which covers most products.

It is better not to. Evening air is often dead calm, and calm air near the ground can trap fine spray droplets and carry them sideways (a temperature inversion). Dew also dilutes the spray. The forecast’s window runs from 7 AM to 7 PM and wants a steady 3–10 mph breeze. More in Best weather to spray weed killer.

The forecast allows up to 90°F and prefers 60–85°F. In heat, weeds under drought stress take up less herbicide, and some products (for example ester forms of 2,4-D) can turn to vapor and drift onto nearby plants. On hot days spray in the morning.

Before crabgrass germinates, which starts when the soil 2 inches down stays around 55°F for several days. In many areas that lines up with forsythia blooming. Most granular pre-emergents then need rain or irrigation to move them into the soil. See When to apply crabgrass preventer.

Below about 45°F most weeds grow too slowly to take up a systemic weed killer well, so the weed killer forecast requires 45°F and prefers 60–85°F. Weeds still green after a frost may need a warmer day. See best weather to spray weed killer.

Many labels suggest not mowing for a few days before spraying, so the weeds have leaf area to absorb the product, and waiting a few days after so it can move through the plant. Check your product label, and pick a day on the weed killer forecast with 6 dry hours after spraying.

It depends on your grass and the forecast. Cool-season lawns (fescue, bluegrass, ryegrass) get most of their feeding in fall and some in spring. Warm-season lawns (Bermuda, zoysia, St. Augustine) are fed from late spring through summer while they grow. The lawn fertilizer forecast checks the weather side: temperature, wind, and whether rain will water it in or wash it away.

About a quarter inch moves granular fertilizer off the grass blades and into the soil. The forecast counts 0.1–0.75 inch within 48 hours as a bonus, and marks a day No if an inch or more is forecast within 24 hours, because that much can wash fertilizer into storm drains.

Yes. Mowing first actually helps, because granules reach the soil instead of sitting in tall grass. Leave the clippings and water the fertilizer in if no light rain is coming.

The lawn fertilizer forecast prefers 50–85°F. Cool-season grasses are usually fed in fall and spring and warm-season grasses while actively growing in late spring and summer. The seasonal calendar covers timing by season.

Light rain right after spreading granular fertilizer is fine and waters it in. Spreading during a downpour or before an inch or more of rain can wash it off the lawn. The forecast marks a day No if an inch or more is forecast within 24 hours. See what rain chances mean.

Wood siding and decks usually need 48 hours of dry weather, longer in cool, humid or shaded spots. Brick and concrete can hold water for days. Do the water drop test on wood or use a moisture meter. Is your deck dry enough to stain? covers both. Then check the paint forecast, which also wants 24 dry hours before you start.

Give it at least 24 hours of dry weather, and 48 if it is cool or the slab is shaded. Sealer over damp concrete or asphalt can turn cloudy or peel. Use the driveway sealing forecast to find the next dry spell.

Not with water in it. Water left in the pump or hoses can freeze and crack them. Drain it, run a pump protector through it, and store it somewhere above freezing. The pressure washing forecast warns when it will freeze within 12 hours of washing. More in Pressure washing in cold weather.

Below about 40°F, or any day with a freeze in the 12 hours after, water left in wood, cracks, siding and the machine can freeze. The pressure washing forecast prefers 50°F or warmer. More in pressure washing in cold weather.

Late morning, so siding and decks have the warm afternoon to dry, especially in spring and fall. Avoid washing in strong wind, which blows spray and cleaner onto plants and windows. The forecast looks for a 3-hour window starting between 9 AM and 3 PM.

Only if the slab and air stay warm enough. Most kits need at least 50°F, many prefer 60°F, and the floor has to stay warm while it cures. The epoxy forecast marks a day No if it drops below 45°F within 24 hours and warns below 55°F. A concrete slab warms much more slowly than the air, so a heated garage needs time to bring the floor up. See Surface vs. air temperature.

Tape a square of clear plastic to the slab and leave it for at least 16 hours. Moisture or a dark patch underneath means water is coming up through the concrete, and epoxy will likely lift. The forecast checks the air (humidity at or below 85% and the slab at least 5°F above the dew point), not moisture inside the slab, so do both checks.

An unheated garage follows the outdoor temperature, and you need the door open for ventilation while you work. Humid outdoor air then condenses on a cold slab, which causes a cloudy, greasy film (amine blush) and poor adhesion. Dew point for painting and staining explains the 5°F rule.

Late spring and early fall, when the slab and the nights are warm but humidity is moderate. Winter slabs are often too cold and humid summer days risk condensation. The garage epoxy forecast checks the 24 hours after you finish for lows below 45–55°F.

Above about 85–90°F epoxy can set in the bucket and on the floor before it levels. Mix small batches, work early in the morning and keep the garage shaded. The forecast caps the work window at 90°F. See the epoxy rules.

Most latex and hybrid exterior caulks need 40°F or higher, and the caulking forecast uses 40°F as its minimum. Some 100% silicone sealants can go on colder if the surface is dry and free of frost. Gaps are at their widest in cold weather, so don’t overfill. See What temperature can you caulk outside?

No. Caulk won’t bond to a wet joint. The forecast wants 12 dry hours before you start, the air at least 5°F above the dew point, and 6 dry hours after you finish, preferably 24.

Yes, up to the label’s limit (often around 100°F), but a joint in hot sun is at its narrowest, so the bead can be stretched in winter. Mild weather is best for both the bond and joint size. See what temperature can you caulk outside.

It depends on the product. Some paintable acrylic and hybrid caulks can be painted within an hour, and others need a day or more, especially when it is cool or humid. Check the tube, and use the caulking forecast to pick a dry day for both jobs.

Most spray paints need 50°F for both the air and the part, and metal left outside overnight stays colder than the air for hours. Bring the piece inside to warm up, and keep the can at room temperature. The spray paint forecast uses 50–90°F with 60–85°F preferred.

Usually humidity. Fast-evaporating solvents cool the surface, and in humid air moisture condenses into the wet paint and leaves a milky haze (blushing). The forecast wants humidity at or below 85%, ideally under 65%, and the air at least 5°F above the dew point.

Most spray paints are dry to the touch within an hour in mild weather but need much longer to harden. The forecast looks for 6 dry hours after you finish and prefers 12. See How long paint needs before it rains.

60–85°F with humidity under about 65% and almost no wind. Most cans allow 50–90°F and up to 85% humidity. The spray paint forecast uses these limits and the complete guide explains why.

Many manufacturers suggest keeping cans at room temperature, and some say a few minutes in warm (not hot) tap water helps. Never use a flame, heater or microwave. A warm can does not fix a cold part or cold air, so check the forecast for a 50°F+ day.