Plain, Washington climate: Climate normals at a NOAA weather station
Plain's normal year runs from 21°F December nights to 82°F July afternoons, with 27.2 inches of precipitation and 117 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 7.7°C, December lows of −6°C, July highs of 28°C, 692 mm of precipitation a year.
- NOAA stationPlain
- Station IDUSC00456534
- Location47.78°N 120.65°W
- Elevation1,936 ft (590 m)
On October 22, the normal high in Plain is 54°F and the normal low 32°F, and the chance of measurable rain or snow is 39%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Plain.
- Jan 34° 21°
- Feb 40° 23°
- Mar 48° 27°
- Apr 57° 32°
- May 67° 39°
- Jun 73° 45°
- Jul 82° 50°
- Aug 82° 49°
- Sep 74° 42°
- Oct 58° 33°
- Nov 42° 27°
- Dec 32° 21°
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 Plain each month?
July is the warmest month, with normal highs of 82°F; December the coldest, with normal lows of 21°F. The most precipitation falls in December (4.97 in), the least in August (0.42 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 34°F | 21°F | 27.5°F | 4.57 | 31.5 | 16 | <1 | 30 | 8 h 50 min |
| February | 40°F | 23°F | 31.4°F | 2.95 | 17.4 | 12 | <1 | 27 | 10 h 10 min |
| March | 48°F | 27°F | 37.4°F | 2.43 | 9.5 | 13 | <1 | 26 | 11 h 50 min |
| April | 57°F | 32°F | 44.5°F | 1.25 | 1.1 | 9 | <1 | 17 | 13 h 40 min |
| May | 67°F | 39°F | 52.9°F | 1.31 | 0.1 | 8 | <1 | 5 | 15 h 10 min |
| June | 73°F | 45°F | 59.0°F | 0.88 | 0.0 | 6 | 1 | <1 | 16 h |
| July | 82°F | 50°F | 66.1°F | 0.48 | 0.0 | 3 | 7 | <1 | 15 h 40 min |
| August | 82°F | 49°F | 65.6°F | 0.42 | 0.0 | 3 | 6 | <1 | 14 h 20 min |
| September | 74°F | 42°F | 57.8°F | 0.79 | 0.0 | 5 | 1 | 3 | 12 h 40 min |
| October | 58°F | 33°F | 45.7°F | 2.61 | 1.0 | 11 | <1 | 14 | 11 h |
| November | 42°F | 27°F | 34.5°F | 4.58 | 14.6 | 16 | <1 | 24 | 9 h 20 min |
| December | 32°F | 21°F | 26.9°F | 4.97 | 42.1 | 17 | <1 | 31 | 8 h 30 min |
| Year (annual) | 57°F | 34°F | 45.8°F | 27.24 | 117.3 | 118 | 16 | 177 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 1°C | −6°C | −2.5°C | 116 mm | 80 cm |
| February | 5°C | −5°C | −0.3°C | 75 mm | 44 cm |
| March | 9°C | −3°C | 3.0°C | 62 mm | 24 cm |
| April | 14°C | 0°C | 6.9°C | 32 mm | 3 cm |
| May | 19°C | 4°C | 11.6°C | 33 mm | 0 cm |
| June | 23°C | 7°C | 15.0°C | 22 mm | 0 cm |
| July | 28°C | 10°C | 18.9°C | 12 mm | 0 cm |
| August | 28°C | 10°C | 18.7°C | 11 mm | 0 cm |
| September | 23°C | 5°C | 14.3°C | 20 mm | 0 cm |
| October | 14°C | 1°C | 7.6°C | 66 mm | 3 cm |
| November | 5°C | −3°C | 1.4°C | 116 mm | 37 cm |
| December | 0°C | −6°C | −2.8°C | 126 mm | 107 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00456534; 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 Plain?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, August has the fewest days with rain (3).
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 USC00456534.
When is the last frost at Plain?
In Plain, the last spring frost (32°F) comes after May 22 in half of years and after June 13 in one year in ten; the first autumn frost comes before September 22 in half of years and before September 7 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 221 year in 10 after June 13; 9 in 10 after May 2
- First autumn frost, half of years before
- September 221 year in 10 before September 7; 9 in 10 before October 4
NOAA puts the median frost-free season at 121 days, and the season without a hard freeze (28°F) at 153 days.
A hard freeze (28°F) comes after May 3 in half of springs and before October 4 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Plain in zone 7a in ZIP code 98822, 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 6b: the coldest night of a typical year reaches −3°F (27 complete years); the map interpolates between stations and terrain, so the station and the ZIP area can differ by half a zone.
Frost dates for every NOAA station in Washington · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00456534; 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 Plain?
In a normal year in Plain, 16 days a year reach 90°F, 177 nights fall to 32°F or colder and 118 days bring measurable precipitation.
- Days at 90°F or more
- 16a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 177a normal year
- Days that stay below freezing
- 33high of 32°F or less
- Days with 0.01 inch of precipitation
- 118a normal year
- Days with 1 inch of snow or more
- 34a normal year
The highest temperature in this station's record (since 1937) is 109°F, on June 30, 2021; the lowest is −31°F, on February 1, 1950.
The wettest calendar year on that record is 1990, with 43.09 in; the snowiest season is 1971–72, with 290.0 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00456534; records: ACIS (NOAA Regional Climate Centers), station USC00456534. Records use complete months only; a month missing more than three days is left out.
How sunny is it at Plain?
Over a year 73% of the sunlight that would reach the ground under clear skies gets through the clouds at Plain, 3.8 kWh per square metre a day. July is the sunniest month (86%) and December the cloudiest (54%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 56% | 1.2 |
| February | 64% | 2.1 |
| March | 63% | 3.1 |
| April | 67% | 4.6 |
| May | 70% | 5.7 |
| June | 74% | 6.3 |
| July | 86% | 7.0 |
| August | 85% | 5.9 |
| September | 79% | 4.3 |
| October | 69% | 2.5 |
| November | 58% | 1.3 |
| December | 54% | 0.9 |
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 Plain record?
A normal year at Plain brings 7,206 heating degree days, 34% more than the median U.S. place (5,373), and 219 cooling degree days, 76% fewer than the median (908). Eight months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 1,691 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,163 | 0 |
| February | 939 | 0 |
| March | 854 | 0 |
| April | 615 | 0 |
| May | 376 | 3 |
| June | 204 | 22 |
| July | 62 | 95 |
| August | 65 | 84 |
| September | 231 | 15 |
| October | 598 | 0 |
| November | 917 | 0 |
| December | 1,181 | 0 |
| Year (annual) | 7,206 | 219 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00456534. 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 Plain been warmer than normal?
2021 averaged 47.0°F, 1.3°F above the 1991-2020 normal of 45.8°F.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 47.0°F | +1.3°F | 24.05 | 123.9 |
Over 51 complete years from 1939 to 2021, the station's annual mean temperature rose at a fitted 3.5°F per century (+0.20°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00456534; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Plain's climate compare?
Plain is warmer than 7 of the 96 places with their own NOAA record in Washington, and wetter than 49. Across the 7,247 U.S. stations with normals, its annual mean of 45.8°F is warmer than 23%.
In the Köppen classification computed from these normals, Plain is Dsb: continental, dry-summer, warm 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 Plain's climate
What is the coldest month at Plain?
December, with a normal high of 32°F and a normal low of 21°F. The warmest is July (82°F by day, 50°F at night).
Does it snow at Plain?
Yes: 117 inches in a normal year, falling on 43 days with 0.1 inch or more, the most in December (42.1 inches).
What is the rainiest month at Plain?
December, with 4.97 in of precipitation in a normal year; the driest is August with 0.42 in.
What plant hardiness zone is Plain in?
The USDA's 2023 map puts Plain in zone 7a in ZIP code 98822, the nearest ZIP area. By the same method at the station, the coldest night of a typical year reaches −3°F (27 years, 1991-2020): zone 6b.
How late can frost come at Plain?
In half of years the last 32°F night comes after May 22; in one year in ten it comes after June 13. Waiting until June 13 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Washington climateThe statewide normals and every place in the state
- Leavenworth, WA16 miles from this station, 47.3°F a year
- Entiat, WA16 miles from this station, 51.4°F a year
- Waterville, WA28 miles from this station, 45.2°F a year
- Holden Village, WA29 miles from this station, 40.9°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made