Washington, Iowa climate: Normal weather by month, frost dates and records
Washington's normal year runs from 12°F January nights to 85°F July afternoons, with 37.9 inches of precipitation and 25 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 9.6°C, January lows of −11°C, July highs of 29°C, 964 mm of precipitation a year.
- NOAA stationWashington
- Station IDUSC00138688
- Location41.28°N 91.71°W
- Elevation687 ft (209 m)
- From the center1 miles
- Population7,281
On October 23, the normal high in Washington is 61°F and the normal low 37°F, and the chance of measurable rain or snow is 28%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Washington.
- Jan 30° 12°
- Feb 35° 15°
- Mar 48° 27°
- Apr 62° 38°
- May 72° 50°
- Jun 81° 60°
- Jul 85° 63°
- Aug 83° 61°
- Sep 77° 51°
- Oct 64° 40°
- Nov 49° 28°
- Dec 36° 18°
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 85°F; January the coldest, with normal lows of 12°F. The most precipitation falls in June (5.17 in), the least in January (1.25 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 30°F | 12°F | 20.8°F | 1.25 | 7.5 | 8 | <1 | 30 | 9 h 30 min |
| February | 35°F | 15°F | 25.1°F | 1.56 | 8.1 | 7 | <1 | 26 | 10 h 40 min |
| March | 48°F | 27°F | 37.4°F | 2.32 | 2.3 | 8 | <1 | 22 | 11 h 50 min |
| April | 62°F | 38°F | 49.7°F | 3.65 | 0.8 | 10 | <1 | 8 | 13 h 20 min |
| May | 72°F | 50°F | 60.9°F | 5.11 | 0.0 | 13 | 1 | 1 | 14 h 30 min |
| June | 81°F | 60°F | 70.6°F | 5.17 | 0.0 | 12 | 4 | <1 | 15 h 10 min |
| July | 85°F | 63°F | 74.1°F | 4.13 | 0.0 | 9 | 8 | <1 | 14 h 50 min |
| August | 83°F | 61°F | 72.0°F | 4.18 | 0.0 | 9 | 5 | <1 | 13 h 50 min |
| September | 77°F | 51°F | 64.3°F | 3.60 | 0.0 | 8 | 2 | <1 | 12 h 30 min |
| October | 64°F | 40°F | 52.0°F | 3.03 | 0.4 | 9 | <1 | 6 | 11 h 10 min |
| November | 49°F | 28°F | 38.2°F | 2.23 | 1.4 | 8 | <1 | 19 | 9 h 50 min |
| December | 36°F | 18°F | 26.7°F | 1.71 | 4.7 | 8 | <1 | 28 | 9 h 10 min |
| Year (annual) | 60°F | 38°F | 49.3°F | 37.94 | 25.2 | 109 | 20 | 140 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −1°C | −11°C | −6.2°C | 32 mm | 19 cm |
| February | 2°C | −9°C | −3.8°C | 40 mm | 21 cm |
| March | 9°C | −3°C | 3.0°C | 59 mm | 6 cm |
| April | 17°C | 3°C | 9.8°C | 93 mm | 2 cm |
| May | 22°C | 10°C | 16.1°C | 130 mm | 0 cm |
| June | 27°C | 15°C | 21.4°C | 131 mm | 0 cm |
| July | 29°C | 17°C | 23.4°C | 105 mm | 0 cm |
| August | 29°C | 16°C | 22.2°C | 106 mm | 0 cm |
| September | 25°C | 11°C | 17.9°C | 91 mm | 0 cm |
| October | 18°C | 4°C | 11.1°C | 77 mm | 1 cm |
| November | 9°C | −2°C | 3.4°C | 57 mm | 4 cm |
| December | 2°C | −8°C | −2.9°C | 43 mm | 12 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00138688; 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 May, June, July, August and September. 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 USC00138688.
When is the last frost in Washington?
In Washington, the last spring frost (32°F) comes after April 28 in half of years and after May 11 in one year in ten; the first autumn frost comes before October 11 in half of years and before September 25 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 281 year in 10 after May 11; 9 in 10 after April 13
- First autumn frost, half of years before
- October 111 year in 10 before September 25; 9 in 10 before October 24
NOAA puts the median frost-free season at 165 days, and the season without a hard freeze (28°F) at 187 days.
A hard freeze (28°F) comes after April 17 in half of springs and before October 22 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Washington in zone 5b in ZIP code 52353, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Washington's NOAA station is in zone 5b: the coldest night of a typical year reaches −14°F (27 complete years).
Frost dates for every NOAA station in Iowa · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00138688; 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 in Washington?
In a normal year in Washington, 20 days a year reach 90°F (1 of them 100°F or more), 140 nights fall to 32°F or colder and 109 days bring measurable precipitation.
- Days at 90°F or more
- 20a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 140a normal year
- Days that stay below freezing
- 45high of 32°F or less
- Days with 0.01 inch of precipitation
- 109a normal year
- Days with 1 inch of snow or more
- 9a normal year
The highest temperature in this station's record (since 1893) is 113°F, on July 15, 1936; the lowest is −32°F, on January 16, 2009.
The wettest calendar year on that record is 1993, with 52.57 in; the snowiest season is 1959–60, with 58.5 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00138688; records: ACIS (NOAA Regional Climate Centers), station USC00138688. Records use complete months only; a month missing more than three days is left out.
How sunny is Washington?
Over a year 74% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Washington, 4.0 kWh per square metre a day. July is the sunniest month (81%) and December the cloudiest (63%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 65% | 1.9 |
| February | 71% | 2.9 |
| March | 69% | 3.8 |
| April | 70% | 4.8 |
| May | 72% | 5.6 |
| June | 77% | 6.2 |
| July | 81% | 6.3 |
| August | 80% | 5.5 |
| September | 81% | 4.6 |
| October | 72% | 3.0 |
| November | 70% | 2.1 |
| December | 63% | 1.5 |
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 6,536 heating degree days, 22% more than the median U.S. place (5,373), and 867 cooling degree days, 4% fewer 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 3,155 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,368 | 0 |
| February | 1,116 | 0 |
| March | 857 | 1 |
| April | 464 | 6 |
| May | 182 | 57 |
| June | 22 | 190 |
| July | 3 | 284 |
| August | 10 | 226 |
| September | 110 | 90 |
| October | 415 | 13 |
| November | 804 | 0 |
| December | 1,186 | 0 |
| Year (annual) | 6,536 | 867 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00138688. 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 51.0°F, 1.7°F above the 1991-2020 normal of 49.3°F. 2 of the 3 complete years since 2022 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2022 | 48.6°F | −0.7°F | 23.94 | 21.4 |
| 2024 | 52.4°F | +3.1°F | 35.88 | 25.1 |
| 2025 | 51.0°F | +1.7°F | 31.71 | 17.3 |
Over 118 complete years from 1884 to 2025, the station's annual mean temperature rose at a fitted 1.9°F per century (+0.10°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00138688; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Washington's climate compare?
Washington is warmer than 92 of the other 131 places with their own NOAA record in Iowa, and wetter than 93. Across the 7,247 U.S. stations with normals, its annual mean of 49.3°F is warmer than 37%.
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?
8 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.
- Wellman, IA1,531 people · 14 mi NW
- Wayland, IA935 people · 10 mi S
- Keota, IA888 people · 14 mi NW
- Brighton, IA592 people · 10 mi SW
- Ainsworth, IA511 people · 8 mi E
- Crawfordsville, IA278 people · 10 mi SE
- West Chester, IA147 people · 7 mi NW
- Coppock, IA35 people · 8 mi S
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 30°F and a normal low of 12°F. The warmest is July (85°F by day, 63°F at night).
Does it snow in Washington?
Yes: 25 inches in a normal year, falling on 16 days with 0.1 inch or more, the most in February (8.1 inches).
What is the rainiest month in Washington?
June, with 5.17 in of precipitation in a normal year; the driest is January with 1.25 in.
What plant hardiness zone is Washington in?
The USDA's 2023 map puts Washington in zone 5b in ZIP code 52353, the nearest ZIP area. By the same method at Washington's NOAA station, the coldest night of a typical year reaches −14°F (27 years, 1991-2020): zone 5b.
How late can frost come in Washington?
In half of years the last 32°F night comes after April 28; in one year in ten it comes after May 11. Waiting until May 11 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Iowa climateThe statewide normals and every place in the state
- Columbus Junction, IA18 miles from this station, 48.8°F a year
- Fairfield, IA22 miles from this station, 49.7°F a year
- Mount Pleasant, IA24 miles from this station, 49.6°F a year
- Iowa City, IA25 miles from this station, 51.0°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made