Washington, Missouri climate: Normal weather by month, frost dates and records
Washington's normal year runs from 20°F January nights to 88°F July afternoons, with 44.1 inches of precipitation and 8 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 12.7°C, January lows of −7°C, July highs of 31°C, 1,120 mm of precipitation a year.
- NOAA stationWashington
- Station IDUSC00238746
- Location38.54°N 90.97°W
- Elevation487 ft (148 m)
- Population15,521
On October 23, the normal high in Washington is 66°F and the normal low 41°F, and the chance of measurable rain or snow is 29%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Washington.
- Jan 40° 20°
- Feb 45° 23°
- Mar 56° 32°
- Apr 67° 43°
- May 76° 54°
- Jun 84° 64°
- Jul 88° 67°
- Aug 87° 65°
- Sep 80° 56°
- Oct 69° 44°
- Nov 55° 33°
- Dec 45° 24°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Washington each month?
July is the warmest month, with normal highs of 88°F; January the coldest, with normal lows of 20°F. The most precipitation falls in May (5.30 in), the least in January (2.52 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 40°F | 20°F | 30.1°F | 2.52 | 2.6 | 8 | <1 | 28 | 9 h 50 min |
| February | 45°F | 23°F | 34.4°F | 2.52 | 1.4 | 8 | <1 | 24 | 10 h 40 min |
| March | 56°F | 32°F | 44.0°F | 3.66 | 0.7 | 11 | <1 | 15 | 11 h 50 min |
| April | 67°F | 43°F | 55.1°F | 4.57 | 0.1 | 11 | 1 | 4 | 13 h 10 min |
| May | 76°F | 54°F | 65.0°F | 5.30 | 0.0 | 13 | 2 | <1 | 14 h 10 min |
| June | 84°F | 64°F | 73.7°F | 4.20 | 0.0 | 10 | 8 | <1 | 14 h 50 min |
| July | 88°F | 67°F | 77.6°F | 4.19 | 0.0 | 8 | 15 | <1 | 14 h 40 min |
| August | 87°F | 65°F | 75.9°F | 3.75 | 0.0 | 8 | 9 | <1 | 13 h 40 min |
| September | 80°F | 56°F | 67.7°F | 3.71 | 0.0 | 8 | 5 | <1 | 12 h 30 min |
| October | 69°F | 44°F | 56.3°F | 3.37 | 0.0 | 9 | <1 | 3 | 11 h 20 min |
| November | 55°F | 33°F | 44.0°F | 3.67 | 0.4 | 8 | <1 | 16 | 10 h 10 min |
| December | 45°F | 24°F | 34.4°F | 2.64 | 2.7 | 8 | <1 | 25 | 9 h 30 min |
| Year (annual) | 66°F | 44°F | 54.8°F | 44.10 | 7.9 | 109 | 40 | 116 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 4°C | −7°C | −1.1°C | 64 mm | 7 cm |
| February | 7°C | −5°C | 1.3°C | 64 mm | 4 cm |
| March | 13°C | 0°C | 6.7°C | 93 mm | 2 cm |
| April | 20°C | 6°C | 12.8°C | 116 mm | 0 cm |
| May | 24°C | 12°C | 18.3°C | 135 mm | 0 cm |
| June | 29°C | 18°C | 23.2°C | 107 mm | 0 cm |
| July | 31°C | 19°C | 25.3°C | 106 mm | 0 cm |
| August | 31°C | 18°C | 24.4°C | 95 mm | 0 cm |
| September | 26°C | 13°C | 19.8°C | 94 mm | 0 cm |
| October | 21°C | 6°C | 13.5°C | 86 mm | 0 cm |
| November | 13°C | 0°C | 6.7°C | 93 mm | 1 cm |
| December | 7°C | −4°C | 1.3°C | 67 mm | 7 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00238746; 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.
When is the best weather to visit Washington?
Normal highs sit between 65°F and 85°F in April, May, June, September and October. Of those, September has the fewest days with rain (8).
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 USC00238746.
When is the last frost in Washington?
In Washington, the last spring frost (32°F) comes after April 8 in half of years and after April 22 in one year in ten; the first autumn frost comes before October 25 in half of years and before October 13 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
- April 81 year in 10 after April 22; 9 in 10 after March 24
- First autumn frost, half of years before
- October 251 year in 10 before October 13; 9 in 10 before November 5
NOAA puts the median frost-free season at 199 days, and the season without a hard freeze (28°F) at 221 days.
A hard freeze (28°F) comes after March 29 in half of springs and before November 4 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Washington in zone 6b in ZIP code 63090.
Frost dates for every NOAA station in Missouri · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00238746; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026. 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 in Washington?
In a normal year in Washington, 40 days a year reach 90°F (2 of them 100°F or more), 116 nights fall to 32°F or colder and 109 days bring measurable precipitation.
- Days at 90°F or more
- 40a normal year
- Days at 100°F or more
- 2a normal year
- Nights at 32°F or colder
- 116a normal year
- Days that stay below freezing
- 21high of 32°F or less
- Days with 0.01 inch of precipitation
- 109a normal year
- Days with 1 inch of snow or more
- 3a normal year
Source: NOAA NCEI 1991-2020 annual normals, station USC00238746.
How sunny is Washington?
Over a year 75% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Washington, 4.2 kWh per square metre a day. July is the sunniest month (82%) and December the cloudiest (66%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 67% | 2.1 |
| February | 66% | 2.8 |
| March | 67% | 3.8 |
| April | 73% | 5.0 |
| May | 74% | 5.6 |
| June | 81% | 6.4 |
| July | 82% | 6.3 |
| August | 81% | 5.6 |
| September | 81% | 4.8 |
| October | 76% | 3.4 |
| November | 72% | 2.4 |
| December | 66% | 1.8 |
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 much heating and cooling does Washington need?
A normal year in Washington brings 4,966 heating degree days, 8% fewer than the median U.S. place (5,373), and 1,298 cooling degree days, 43% more than the median (908). Seven months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 3,948 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,083 | 0 |
| February | 857 | 0 |
| March | 655 | 3 |
| April | 315 | 17 |
| May | 107 | 107 |
| June | 6 | 266 |
| July | 1 | 392 |
| August | 2 | 339 |
| September | 62 | 143 |
| October | 300 | 29 |
| November | 630 | 2 |
| December | 948 | 0 |
| Year (annual) | 4,966 | 1,298 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00238746. 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.
Has Washington been warmer than normal lately?
2025 averaged 56.3°F, 1.5°F above the 1991-2020 normal of 54.8°F. 4 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 55.9°F | +1.1°F | 35.19 | – |
| 2022 | 54.6°F | −0.2°F | 41.30 | – |
| 2023 | 56.9°F | +2.1°F | 31.33 | – |
| 2024 | 57.6°F | +2.8°F | 57.90 | – |
| 2025 | 56.3°F | +1.5°F | 39.13 | 14.4 |
Source: observed years: ACIS, station USC00238746. A year counts only with all twelve months complete.
How does Washington's climate compare?
Washington is warmer than 55 of the other 133 places with their own NOAA record in Missouri, and wetter than 65. Across the 7,247 U.S. stations with normals, its annual mean of 54.8°F is warmer than 59%.
In the Köppen classification computed from these normals, Washington is Dfa: continental, no dry season, hot 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.
Which places near Washington share this climate record?
5 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Pacific, MO7,842 people · 13 mi E
- Gray Summit, MO2,847 people · 9 mi E
- Marthasville, MO1,302 people · 8 mi NW
- Augusta, MO268 people · 5 mi E
- Three Creeks, MO8 people · 2 mi NW
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about Washington's climate
What is the coldest month in Washington?
January, with a normal high of 40°F and a normal low of 20°F. The warmest is July (88°F by day, 67°F at night).
Does it snow in Washington?
Yes: 8 inches in a normal year, falling on 5 days with 0.1 inch or more, the most in December (2.7 inches).
What is the rainiest month in Washington?
May, with 5.30 in of precipitation in a normal year; the driest is January with 2.52 in.
What plant hardiness zone is Washington in?
The USDA's 2023 map puts Washington in zone 6b in ZIP code 63090.
How late can frost come in Washington?
In half of years the last 32°F night comes after April 8; in one year in ten it comes after April 22. Waiting until April 22 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Missouri climateThe statewide normals and every place in the state
- Union, MO7 miles from this station, 56.9°F a year
- St Louis Spirit of St. Louis Airport, MO19 miles from this station, 56.1°F a year
- Weldon Spring, MO19 miles from this station, 55.2°F a year
- Warrenton, MO22 miles from this station, 54.5°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made