Ottumwa climate — normals and trends
Ottumwa (United States) has a hot-summer humid continental climate (Dfa) under the Köppen-Geiger classification. Its mean annual temperature is 10.5 °C and it receives 911 mm of precipitation per year.
These figures are normals computed over 86 complete calendar years, from 1940 to 2025, using ERA5 reanalysis data from the Copernicus programme.
The warmest month is July (24.4 °C on average) and the coldest is January (-5.5 °C). Rainfall peaks in May.
Ottumwa averages 118 frost days, 40 hot days (≥ 30 °C) and 107 rainy days per year.
Ottumwa has warmed by +1.8 °C between 1940 and 2025, or +0.21 °C per decade. This trend is statistically significant.
The number of frost days there went from about 128 to 108 per year over the period.
The hottest day of the period reached 40.4 °C (on 21 June 2022) and the coldest -33.9 °C (on 3 February 1996).
Data from ERA5 reanalysis (Copernicus Climate Change Service), redistributed under a CC-BY 4.0 licence. Normals are recomputed whenever the archive is updated.
Climate normals · ERA5
OttumwaIowa
- coords
- 41.02°, -92.41°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
10.5°C
Average daily high
15.6°C
Average daily low
5.6°C
Annual rainfall
911mm
Sunshine / day
8.9h
Mean relative humidity
70%
Average peak wind
21.0km/h
Seasonal range
29.9°C
Frost days (< 0 °C)
118 d/yr
Hot days (≥ 30 °C)
40 d/yr
Rainy days (≥ 1 mm)
107 d/yr
Annual snowfall
63.2 cm
Average feels-like high
13.5 °C
Average feels-like low
2.7 °C
Average peak gust
39.2 km/h
Tropical nights (≥ 20 °C)
36 d/yr
Solar radiation
15.4 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.8 °C
since 1940
+0.2 °C per decade · r² = 0.28 · p = < 0.001
Trend fitted by linear regression (ordinary least squares) on annual means. A trend is shown only when it is statistically significant (p < 0.05).
A climograph overlays rainfall (bars) and temperature (line): the standard reading in climatology, where you can see at a glance whether the warm season is also the dry one.
Records for the period
Hottest day
40.4 °C
21 June 2022
Coldest day
-33.9 °C
3 February 1996
Wettest day
122 mm
13 September 1961
Windiest day
68.1 km/h
9 April 1973
Strongest gust
111.2 km/h
15 December 2021
Hottest feels-like
45.7 °C
6 July 1948
Coldest feels-like
-39.6 °C
3 February 1996
Snowiest day
35.2 cm
9 April 1973
Sunniest day
14.6 h
1 July 2025
Normals computed over complete calendar years 1940–2025.
A specific year
Pick a year and see how it compares to normal — warmer, drier or more extreme than usual?
Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | -0.2 °C | +0.9 °C | 38 mm | -0 mm |
| Feb | 1.3 °C | -0.4 °C | 13 mm | -27 mm |
| Mar | 15.3 °C | +6.7 °C | 67 mm | -8 mm |
| Apr | 17.7 °C | +1.6 °C | 166 mm | +64 mm |
| May | 23.4 °C | +1.4 °C | 61 mm | -51 mm |
| Jun | 29.3 °C | +2.0 °C | 128 mm | +16 mm |
| Jul | 30.6 °C | +1.1 °C | 173 mm | +83 mm |
| Aug | 28.1 °C | -0.4 °C | 57 mm | -31 mm |
| Sep | 28.0 °C | +3.5 °C | 49 mm | -39 mm |
| Oct | 21.6 °C | +3.5 °C | 47 mm | -23 mm |
| Nov | 11.3 °C | +1.9 °C | 43 mm | -11 mm |
| Dec | 2.9 °C | +0.9 °C | 32 mm | -11 mm |
The year's extremes
What was the weather like that day?
Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.
Frequently asked questions
What is the climate of Ottumwa?
Ottumwa has a hot-summer humid continental climate (Köppen Dfa). Over 1940-2025, the average annual temperature is 10.5 °C and it receives 911 mm of precipitation per year.
What is the hottest day ever recorded in Ottumwa?
The hottest day measured in Ottumwa between 1940 and 2025 was 21 June 2022, reaching 40.4 °C.
What is the coldest day in Ottumwa?
The coldest day measured in Ottumwa between 1940 and 2025 was 3 February 1996, at -33.9 °C.
Does it snow in Ottumwa?
Yes. Ottumwa gets on average 63.2 cm of snow per year and has around 118 frost days.
Has the climate of Ottumwa warmed?
Yes: Ottumwa warmed by +1.8 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Ottumwa?
The wettest day measured in Ottumwa between 1940 and 2025 was 13 September 1961, with 122 mm of rain in 24 hours.
What was the windiest day in Ottumwa?
The windiest day measured in Ottumwa between 1940 and 2025 was 9 April 1973, with winds reaching 68.1 km/h.
What is the warmest month in Ottumwa?
The warmest month in Ottumwa is July (24.4 °C on average); the coldest is January (-5.5 °C).
How much does it rain in Ottumwa?
Ottumwa receives on average 911 mm of precipitation per year, spread over about 107 rainy days.
Is it sunny in Ottumwa?
Ottumwa gets on average 8.9 hours of sunshine per day, roughly 3,249 hours per year over 1940-2025.
What is the biggest single-day snowfall in Ottumwa?
The heaviest 24-hour snowfall measured in Ottumwa between 1940 and 2025 was 9 April 1973, with 35.2 cm.
Are there tropical nights in Ottumwa?
Yes: Ottumwa has on average 36 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Ottumwa?
In Ottumwa, between 1940 and 2025, the highest apparent temperature reached 45.7 °C on 6 July 1948, and the lowest was -39.6 °C on 3 February 1996.
Compare Ottumwa with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Ottumwa