Des Moines Weather Office-Johnston, Iowa climate: Climate normals at a NOAA weather station
Des Moines Weather Office-Johnston's normal year runs from 13°F January nights to 85°F July afternoons, with 36.2 inches of precipitation and 38 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 10.2°C, January lows of −10°C, July highs of 29°C, 918 mm of precipitation a year.
- NOAA stationDes Moines Weather Office-Johnston
- Station IDUSC00132209
- Location41.74°N 93.72°W
- Elevation959 ft (292 m)
On October 23, the normal high in Des Moines Weather Office-Johnston is 60°F and the normal low 40°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 Des Moines Weather Office-Johnston.
- Jan 30° 13°
- Feb 35° 17°
- Mar 49° 29°
- Apr 62° 40°
- May 72° 52°
- Jun 81° 62°
- Jul 85° 66°
- Aug 83° 64°
- Sep 76° 55°
- Oct 63° 43°
- Nov 48° 30°
- Dec 35° 19°
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 Des Moines Weather Office-Johnston each month?
July is the warmest month, with normal highs of 85°F; January the coldest, with normal lows of 13°F. The most precipitation falls in June (5.35 in), the least in January (1.01 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 30°F | 13°F | 21.5°F | 1.01 | 9.7 | 8 | <1 | 30 | 9 h 30 min |
| February | 35°F | 17°F | 26.2°F | 1.25 | 10.5 | 8 | <1 | 25 | 10 h 30 min |
| March | 49°F | 29°F | 38.7°F | 2.15 | 5.0 | 9 | <1 | 21 | 11 h 50 min |
| April | 62°F | 40°F | 50.8°F | 4.00 | 1.6 | 11 | <1 | 7 | 13 h 20 min |
| May | 72°F | 52°F | 61.8°F | 4.84 | 0.2 | 13 | 1 | <1 | 14 h 30 min |
| June | 81°F | 62°F | 71.5°F | 5.35 | 0.0 | 12 | 3 | <1 | 15 h 10 min |
| July | 85°F | 66°F | 75.2°F | 4.27 | 0.0 | 9 | 8 | <1 | 15 h |
| August | 83°F | 64°F | 73.2°F | 3.97 | 0.0 | 10 | 4 | <1 | 13 h 50 min |
| September | 76°F | 55°F | 65.6°F | 3.40 | 0.0 | 8 | 2 | <1 | 12 h 30 min |
| October | 63°F | 43°F | 52.8°F | 2.51 | 0.5 | 9 | <1 | 5 | 11 h 10 min |
| November | 48°F | 30°F | 38.8°F | 1.95 | 2.2 | 7 | <1 | 18 | 9 h 50 min |
| December | 35°F | 19°F | 27.1°F | 1.46 | 8.3 | 8 | <1 | 28 | 9 h 10 min |
| Year (annual) | 60°F | 41°F | 50.3°F | 36.16 | 38.0 | 112 | 18 | 135 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −1°C | −10°C | −5.8°C | 26 mm | 25 cm |
| February | 2°C | −8°C | −3.2°C | 32 mm | 27 cm |
| March | 9°C | −2°C | 3.7°C | 55 mm | 13 cm |
| April | 16°C | 5°C | 10.4°C | 102 mm | 4 cm |
| May | 22°C | 11°C | 16.6°C | 123 mm | 1 cm |
| June | 27°C | 17°C | 21.9°C | 136 mm | 0 cm |
| July | 29°C | 19°C | 24.0°C | 108 mm | 0 cm |
| August | 28°C | 18°C | 22.9°C | 101 mm | 0 cm |
| September | 25°C | 13°C | 18.7°C | 86 mm | 0 cm |
| October | 17°C | 6°C | 11.6°C | 64 mm | 1 cm |
| November | 9°C | −1°C | 3.8°C | 50 mm | 6 cm |
| December | 2°C | −7°C | −2.7°C | 37 mm | 21 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00132209; 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 Des Moines Weather Office-Johnston?
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 USC00132209.
When is the last frost at Des Moines Weather Office-Johnston?
In Des Moines Weather Office-Johnston, the last spring frost (32°F) comes after April 19 in half of years and after May 3 in one year in ten; the first autumn frost comes before October 18 in half of years and before October 1 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 191 year in 10 after May 3; 9 in 10 after April 5
- First autumn frost, half of years before
- October 181 year in 10 before October 1; 9 in 10 before October 30
NOAA puts the median frost-free season at 179 days, and the season without a hard freeze (28°F) at 199 days.
A hard freeze (28°F) comes after April 9 in half of springs and before October 27 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Des Moines Weather Office-Johnston in zone 5b in ZIP code 50131, 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 5b: the coldest night of a typical year reaches −15°F (25 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 USC00132209; 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 Des Moines Weather Office-Johnston?
In a normal year in Des Moines Weather Office-Johnston, 18 days a year reach 90°F, 135 nights fall to 32°F or colder and 112 days bring measurable precipitation.
- Days at 90°F or more
- 18a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 135a normal year
- Days that stay below freezing
- 50high of 32°F or less
- Days with 0.01 inch of precipitation
- 112a normal year
- Days with 1 inch of snow or more
- 12a normal year
The highest temperature in this station's record (since 1995) is 104°F, on July 23, 2012; the lowest is −27°F, on February 2, 1996.
The wettest calendar year on that record is 2010, with 59.21 in; the snowiest season is 2009–10, with 58.5 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00132209; records: ACIS (NOAA Regional Climate Centers), station USC00132209. Records use complete months only; a month missing more than three days is left out.
How sunny is it at Des Moines Weather Office-Johnston?
Over a year 75% of the sunlight that would reach the ground under clear skies gets through the clouds at Des Moines Weather Office-Johnston, 4.1 kWh per square metre a day. July is the sunniest month (81%) and December the cloudiest (68%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 68% | 2.0 |
| February | 74% | 3.0 |
| March | 70% | 3.8 |
| April | 69% | 4.8 |
| May | 72% | 5.7 |
| June | 77% | 6.3 |
| July | 81% | 6.4 |
| August | 80% | 5.5 |
| September | 80% | 4.6 |
| October | 73% | 3.1 |
| November | 72% | 2.2 |
| December | 68% | 1.7 |
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 Des Moines Weather Office-Johnston record?
A normal year at Des Moines Weather Office-Johnston brings 6,317 heating degree days, 18% more than the median U.S. place (5,373), and 988 cooling degree days, 9% 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 3,361 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,347 | 0 |
| February | 1,086 | 0 |
| March | 817 | 2 |
| April | 435 | 9 |
| May | 162 | 63 |
| June | 17 | 210 |
| July | 3 | 317 |
| August | 6 | 261 |
| September | 91 | 111 |
| October | 394 | 16 |
| November | 786 | 0 |
| December | 1,175 | 0 |
| Year (annual) | 6,317 | 988 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00132209. 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 Des Moines Weather Office-Johnston been warmer than normal?
2025 averaged 51.8°F, 1.5°F above the 1991-2020 normal of 50.3°F. 4 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 52.2°F | +1.9°F | 29.86 | 34.9 |
| 2022 | 49.9°F | −0.4°F | 31.55 | 37.7 |
| 2023 | 52.5°F | +2.2°F | 28.27 | 25.2 |
| 2024 | 53.5°F | +3.2°F | 36.83 | 30.1 |
| 2025 | 51.8°F | +1.5°F | 37.72 | 31.5 |
Source: observed years: ACIS, station USC00132209. A year counts only with all twelve months complete.
How does Des Moines Weather Office-Johnston's climate compare?
Des Moines Weather Office-Johnston is warmer than 113 of the 132 places with their own NOAA record in Iowa, and wetter than 55. Across the 7,247 U.S. stations with normals, its annual mean of 50.3°F is warmer than 42%.
In the Köppen classification computed from these normals, Des Moines Weather Office-Johnston 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 Des Moines Weather Office-Johnston share this climate record?
7 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.
- Urbandale, IA47,759 people · 8 mi SW
- Johnston, IA25,022 people · 3 mi S
- Grimes, IA17,266 people · 6 mi SW
- Polk City, IA6,430 people · 3 mi N
- Madrid, IA2,824 people · 11 mi NW
- Granger, IA2,095 people · 5 mi W
- Sheldahl, IA312 people · 9 mi N
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 Des Moines Weather Office-Johnston's climate
What is the coldest month at Des Moines Weather Office-Johnston?
January, with a normal high of 30°F and a normal low of 13°F. The warmest is July (85°F by day, 66°F at night).
Does it snow at Des Moines Weather Office-Johnston?
Yes: 38 inches in a normal year, falling on 26 days with 0.1 inch or more, the most in February (10.5 inches).
What is the rainiest month at Des Moines Weather Office-Johnston?
June, with 5.35 in of precipitation in a normal year; the driest is January with 1.01 in.
What plant hardiness zone is Des Moines Weather Office-Johnston in?
The USDA's 2023 map puts Des Moines Weather Office-Johnston in zone 5b in ZIP code 50131, the nearest ZIP area. By the same method at the station, the coldest night of a typical year reaches −15°F (25 years, 1991-2020): zone 5b.
How late can frost come at Des Moines Weather Office-Johnston?
In half of years the last 32°F night comes after April 19; in one year in ten it comes after May 3. Waiting until May 3 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Iowa climateThe statewide normals and every place in the state
- Ankeny, IA4 miles from this station, 49.5°F a year
- Des Moines, IA14 miles from this station, 50.9°F a year
- Ames, IA19 miles from this station, 48.5°F a year
- Perry, IA21 miles from this station, 48.9°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made