Alaska weather and outdoor projects
Alaska’s outdoor season is short and varies enormously by region. Anchorage has cool summers and a moderate coastal climate, while Fairbanks in the Interior has warm, dry summer days and some of the coldest winters in the country. In much of the state, the window for paint, stain and concrete is roughly late May to early September.
Long summer daylight helps, because drying can continue into the evening, but cool nights still slow cure times. Late summer in Southcentral Alaska is often the rainiest part of the year, so June and early July are usually the best bet for staining and painting. Permafrost and frost heave affect slabs and footings in the Interior, and local building guidance for frost depth matters more than weather timing there.
Frost dates in Alaska
In Anchorage, the median last spring freeze (32°F) is around May 5 and the median first fall freeze is around October 1, a frost-free season of about 147 days.
In Fairbanks, the median last spring freeze (32°F) is around May 13 and the median first fall freeze is around September 13, a frost-free season of about 121 days.
How Alaska compares with other states
Anchorage has the most freezing nights of the 50 state main stations (186 a year). Anchorage has the fewest days at 90°F or hotter of the 50 state main stations (0 a year). Anchorage has the 4th-shortest frost-free season of the 50 state main stations (147 days).
| Measure (Anchorage) | Value | Rank, highest first |
|---|---|---|
| Deck staining season | 3 good months | 38th of 50 |
| Frost-free season | 147 days | 47th of 50 |
| Freezing nights | 186 a year | 1st of 50 |
| Rainy days | 49 a year with 0.1 in or more | 39th of 50 |
| Days at 90°F or hotter | 0 a year | 50th of 50 |
| Summer afternoons | 60% humidity at 3 PM, June–August | 4th of 47 |
Best time to stain a deck in Alaska
In Anchorage, the most reliable months are June–August. May and September can also work on the right days (average highs May 56°F, Sep 56°F). October–April is too cold, with average highs around 32°F. May and September are cool, with highs around 56°F, so choose the warmest afternoons.
In Fairbanks, the most reliable months are June–July. May and August can also work on the right days (average highs May 62°F, Aug 66°F). October–April is too cold, with average highs around 19°F. In September, nights average about 36°F, too cold for the coating to dry and cure overnight. In May and August, nights average about 43°F, so finish early on mild days and check the overnight low.
Best time to paint outside in Alaska
In Anchorage, the most reliable months are June–August. May and September can also work on the right days (average highs May 56°F, Sep 56°F). October–April is too cold, with average highs around 32°F. May and September are cool, with highs around 56°F, so choose the warmest afternoons.
In Fairbanks, the most reliable months are June–August. May and September can also work on the right days (average highs May 62°F, Sep 55°F). October–April is too cold, with average highs around 19°F. In May, nights average about 39°F, so finish early on mild days and check the overnight low. September is cool, with highs around 55°F, so choose the warmest afternoons.
Best time to pour concrete in Alaska
In Anchorage, the most reliable months are June–August. May and September can also work on the right days (average highs May 56°F, Sep 56°F). October–April averages about 26 nights a month at or below 32°F, so fresh concrete needs blankets or heated enclosures. May and September bring about 3 freezing nights a month, so pick a mild spell and keep curing blankets on hand.
In Fairbanks, the most reliable months are June–August. May can also work on the right days (average highs May 62°F). September–April averages about 27 nights a month at or below 32°F, so fresh concrete needs blankets or heated enclosures. May brings about 6 freezing nights a month, so pick a mild spell and keep curing blankets on hand.
Best time to seal a driveway in Alaska
Anchorage has no month that is easy for this job on average; the best chances come in June–August. September–May is too cold, with average highs around 37°F. June–August is cool, with highs around 65°F, so choose the warmest afternoons.
In Fairbanks, the most reliable months are July. June and August can also work on the right days (average highs Jun 72°F, Aug 66°F). September–April is too cold, with average highs around 24°F. In May, nights average about 39°F, too cold for the coating to dry and cure overnight. In June, nights average about 50°F, so finish early on mild days and check the overnight low. August is cool, with highs around 66°F, so choose the warmest afternoons.
Best time to fertilize or treat a lawn in Alaska
In Anchorage, the most reliable months are June–August. May and September can also work on the right days (average highs May 56°F, Sep 56°F). October–April is too cold, with average highs around 32°F. May and September are cool, with highs around 56°F, so choose the warmest afternoons.
In Fairbanks, the most reliable months are May–August. September can also work on the right days (average highs Sep 55°F). October–April is too cold, with average highs around 19°F. September is cool, with highs around 55°F, so choose the warmest afternoons.
How the weather differs across Alaska
| Place | Hottest month avg high | Coldest month avg low | Rain per year | Last spring freeze | First fall freeze |
|---|---|---|---|---|---|
| Anchorage | 66°F | 11°F | 16 in | May 5 | October 1 |
| Fairbanks | 73°F | -17°F | 12 in | May 13 | September 13 |
Of the places above, Anchorage has the most good months for staining, painting and concrete combined (9 job-months), and Fairbanks has the fewest (8).
Monthly weather in Anchorage
| Month | Avg high | Avg low | Wet days* | Rain | 3 PM humidity | Freezing nights |
|---|---|---|---|---|---|---|
| January | 23°F | 11°F | 3 | 0.8 in | 74% | 30 |
| February | 27°F | 15°F | 3 | 0.9 in | 68% | 27 |
| March | 33°F | 19°F | 2 | 0.7 in | 55% | 29 |
| April | 45°F | 30°F | 1 | 0.4 in | 51% | 19 |
| May | 56°F | 40°F | 2 | 0.7 in | 48% | 3 |
| June | 63°F | 48°F | 3 | 1.0 in | 55% | 0 |
| July | 66°F | 53°F | 5 | 1.8 in | 62% | 0 |
| August | 64°F | 51°F | 8 | 2.9 in | 64% | 0 |
| September | 56°F | 43°F | 8 | 3.1 in | 63% | 3 |
| October | 42°F | 31°F | 5 | 1.8 in | 65% | 18 |
| November | 29°F | 18°F | 4 | 1.2 in | 72% | 27 |
| December | 25°F | 14°F | 4 | 1.2 in | 77% | 31 |
*Days with 0.1 inch of rain or more; column notes.
Monthly weather in Fairbanks
| Month | Avg high | Avg low | Wet days* | Rain | 3 PM humidity | Freezing nights |
|---|---|---|---|---|---|---|
| January | 1°F | -17°F | 2 | 0.6 in | 93% | 31 |
| February | 12°F | -11°F | 2 | 0.5 in | 73% | 28 |
| March | 25°F | -3°F | 1 | 0.4 in | 49% | 31 |
| April | 46°F | 22°F | 1 | 0.3 in | 38% | 26 |
| May | 62°F | 39°F | 2 | 0.5 in | 32% | 6 |
| June | 72°F | 50°F | 5 | 1.5 in | 39% | 0 |
| July | 73°F | 53°F | 6 | 2.3 in | 47% | 0 |
| August | 66°F | 48°F | 6 | 2.1 in | 52% | 0 |
| September | 55°F | 36°F | 4 | 1.4 in | 52% | 9 |
| October | 34°F | 18°F | 3 | 0.8 in | 65% | 29 |
| November | 12°F | -4°F | 2 | 0.7 in | 80% | 30 |
| December | 4°F | -13°F | 2 | 0.6 in | 86% | 31 |
Source: NOAA NCEI U.S. Climate Normals 1991–2020 for ANCHORAGE INTL AP, FAIRBANKS INTL AP. See how the ratings work and how late in fall you can stain, paint or seal.
Frequently asked questions
When is the best time to stain a deck in Alaska?
In Anchorage, June–August. In Fairbanks, June–July.
When is the last frost in Alaska?
Anchorage: around May 5; Fairbanks: around May 13.
Can you pour concrete in winter in Alaska?
Yes, with cold-weather practices: Anchorage averages about 88 freezing nights from December to February, so fresh concrete needs insulated blankets, a heated enclosure or an accelerated mix, and must not freeze in the first 48 hours. Many homeowners wait for spring.
What months are best for sealing a driveway in Alaska?
In Anchorage, conditions are marginal in most months, so choose warm, dry spells. In Fairbanks, July.