Fort Richardson Water Treatment Plant, Alaska climate: Climate normals at a NOAA weather station
Fort Richardson Water Treatment Plant's normal year runs from 8°F January nights to 66°F July afternoons, with 15.7 inches of precipitation and 59 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 2.3°C, January lows of −13°C, July highs of 19°C, 400 mm of precipitation a year.
- NOAA stationFort Richardson Water Treatment Plant
- Station IDUSC00503163
- Location61.23°N 149.65°W
- Elevation470 ft (143 m)
On October 23, the normal high in Fort Richardson Water Treatment Plant is 38°F and the normal low 24°F, and the chance of measurable rain or snow is 31%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Fort Richardson Water Treatment Plant.
- Jan 21° 8°
- Feb 28° 12°
- Mar 33° 15°
- Apr 46° 28°
- May 57° 38°
- Jun 64° 46°
- Jul 66° 50°
- Aug 64° 48°
- Sep 55° 40°
- Oct 42° 28°
- Nov 28° 15°
- Dec 24° 11°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like at Fort Richardson Water Treatment Plant each month?
July is the warmest month, with normal highs of 66°F; January the coldest, with normal lows of 8°F. The most precipitation falls in September (2.70 in), the least in April (0.36 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 21°F | 8°F | 14.8°F | 0.61 | 9.8 | 6 | <1 | 30 | 6 h 20 min |
| February | 28°F | 12°F | 20.0°F | 0.87 | 10.3 | 7 | <1 | 28 | 9 h |
| March | 33°F | 15°F | 23.9°F | 0.68 | 10.7 | 6 | <1 | 30 | 11 h 40 min |
| April | 46°F | 28°F | 36.5°F | 0.36 | 1.5 | 3 | <1 | 21 | 14 h 40 min |
| May | 57°F | 38°F | 47.2°F | 0.68 | 0.4 | 6 | <1 | 4 | 17 h 20 min |
| June | 64°F | 46°F | 54.8°F | 1.10 | 0.0 | 8 | <1 | <1 | 19 h 20 min |
| July | 66°F | 50°F | 58.2°F | 2.01 | 0.0 | 12 | <1 | <1 | 18 h 30 min |
| August | 64°F | 48°F | 55.9°F | 2.48 | 0.0 | 14 | <1 | <1 | 16 h |
| September | 55°F | 40°F | 47.7°F | 2.70 | 0.1 | 14 | <1 | 4 | 13 h |
| October | 42°F | 28°F | 34.7°F | 1.67 | 4.4 | 11 | <1 | 21 | 10 h 10 min |
| November | 28°F | 15°F | 21.4°F | 1.18 | 9.0 | 8 | <1 | 29 | 7 h 20 min |
| December | 24°F | 11°F | 17.6°F | 1.40 | 13.2 | 8 | <1 | 31 | 5 h 30 min |
| Year (annual) | 44°F | 28°F | 36.1°F | 15.74 | 59.4 | 102 | <1 | 198 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −6°C | −13°C | −9.6°C | 15 mm | 25 cm |
| February | −2°C | −11°C | −6.7°C | 22 mm | 26 cm |
| March | 1°C | −10°C | −4.5°C | 17 mm | 27 cm |
| April | 8°C | −2°C | 2.5°C | 9 mm | 4 cm |
| May | 14°C | 3°C | 8.4°C | 17 mm | 1 cm |
| June | 18°C | 8°C | 12.7°C | 28 mm | 0 cm |
| July | 19°C | 10°C | 14.6°C | 51 mm | 0 cm |
| August | 18°C | 9°C | 13.3°C | 63 mm | 0 cm |
| September | 13°C | 4°C | 8.7°C | 69 mm | 0 cm |
| October | 5°C | −2°C | 1.5°C | 42 mm | 11 cm |
| November | −2°C | −9°C | −5.9°C | 30 mm | 23 cm |
| December | −4°C | −12°C | −8.0°C | 36 mm | 34 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00503163; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
Which months are mildest at Fort Richardson Water Treatment Plant?
Normal highs sit between 65°F and 85°F in July.
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00503163.
When is the last frost at Fort Richardson Water Treatment Plant?
In Fort Richardson Water Treatment Plant, the last spring frost (32°F) comes after May 9 in half of years and after May 22 in one year in ten; the first autumn frost comes before September 26 in half of years and before September 9 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- May 91 year in 10 after May 22; 9 in 10 after April 28
- First autumn frost, half of years before
- September 261 year in 10 before September 9; 9 in 10 before October 10
NOAA puts the median frost-free season at 138 days, and the season without a hard freeze (28°F) at 162 days.
A hard freeze (28°F) comes after April 28 in half of springs and before October 6 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Fort Richardson Water Treatment Plant in zone 5a in ZIP code 99504, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, the station is in zone 5a: the coldest night of a typical year reaches −15°F (20 complete years).
Frost dates for every NOAA station in Alaska · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00503163; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
How hot and how cold does it get at Fort Richardson Water Treatment Plant?
In a normal year in Fort Richardson Water Treatment Plant, a 90°F day is rare, 198 nights fall to 32°F or colder and 102 days bring measurable precipitation.
- Days at 90°F or more
- fewer than 1a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 198a normal year
- Days that stay below freezing
- 104high of 32°F or less
- Days with 0.01 inch of precipitation
- 102a normal year
- Days with 1 inch of snow or more
- 19a normal year
Source: NOAA NCEI 1991-2020 annual normals, station USC00503163.
How sunny is it at Fort Richardson Water Treatment Plant?
Over a year 64% of the sunlight that would reach the ground under clear skies gets through the clouds at Fort Richardson Water Treatment Plant, 2.5 kWh per square metre a day. April is the sunniest month (70%) and October the cloudiest (55%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 57% | 0.3 |
| February | 59% | 0.9 |
| March | 68% | 2.4 |
| April | 70% | 4.0 |
| May | 66% | 5.0 |
| June | 65% | 5.3 |
| July | 63% | 4.8 |
| August | 63% | 3.8 |
| September | 61% | 2.4 |
| October | 55% | 1.1 |
| November | 55% | 0.4 |
| December | 56% | 0.1 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How many heating and cooling degree days does Fort Richardson Water Treatment Plant record?
A normal year at Fort Richardson Water Treatment Plant brings 10,542 heating degree days, 96% more than the median U.S. place (5,373), and 8 cooling degree days, 99% fewer than the median (908). Ten months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 668 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,556 | 0 |
| February | 1,260 | 0 |
| March | 1,274 | 0 |
| April | 854 | 0 |
| May | 553 | 0 |
| June | 308 | 2 |
| July | 216 | 5 |
| August | 283 | 1 |
| September | 519 | 0 |
| October | 938 | 0 |
| November | 1,309 | 0 |
| December | 1,471 | 0 |
| Year (annual) | 10,542 | 8 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00503163. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Have recent years at Fort Richardson Water Treatment Plant been warmer than normal?
2025 averaged 38.1°F, 2.0°F above the 1991-2020 normal of 36.1°F. 2 of the 4 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 34.0°F | −2.1°F | 19.04 | – |
| 2023 | 35.9°F | −0.2°F | – | – |
| 2024 | 36.3°F | +0.2°F | – | – |
| 2025 | 38.1°F | +2.0°F | 17.13 | 23.6 |
Source: observed years: ACIS, station USC00503163. A year counts only with all twelve months complete.
How does Fort Richardson Water Treatment Plant's climate compare?
Fort Richardson Water Treatment Plant is warmer than 48 of the 85 places with their own NOAA record in Alaska, and wetter than 25. Across the 7,247 U.S. stations with normals, its annual mean of 36.1°F is warmer than 2%.
In the Köppen classification computed from these normals, Fort Richardson Water Treatment Plant is Dsc: continental, dry-summer, cool summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Questions about Fort Richardson Water Treatment Plant's climate
What is the coldest month at Fort Richardson Water Treatment Plant?
January, with a normal high of 21°F and a normal low of 8°F. The warmest is July (66°F by day, 50°F at night).
Does it snow at Fort Richardson Water Treatment Plant?
Yes: 59 inches in a normal year, falling on 28 days with 0.1 inch or more, the most in December (13.2 inches).
What is the rainiest month at Fort Richardson Water Treatment Plant?
September, with 2.70 in of precipitation in a normal year; the driest is April with 0.36 in.
What plant hardiness zone is Fort Richardson Water Treatment Plant in?
The USDA's 2023 map puts Fort Richardson Water Treatment Plant in zone 5a in ZIP code 99504, the nearest ZIP area. By the same method at the station, the coldest night of a typical year reaches −15°F (20 years, 1991-2020): zone 5a.
How late can frost come at Fort Richardson Water Treatment Plant?
In half of years the last 32°F night comes after May 9; in one year in ten it comes after May 22. Waiting until May 22 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Alaska climateThe statewide normals and every place in the state
- Campbell Creek Science Center, AK6 miles from this station, 34.1°F a year
- Eagle River Gakona Circle, AK7 miles from this station, 36.1°F a year
- Eagle River (5 mi SE), AK9 miles from this station, 36.7°F a year
- Glen Alps, AK9 miles from this station, 34.5°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made