Marshalltown climate — normals and trends
Marshalltown (United States) has a hot-summer humid continental climate (Dfa) under the Köppen-Geiger classification. Its mean annual temperature is 9.1 °C and it receives 922 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 (23.2 °C on average) and the coldest is January (-7.4 °C). Rainfall peaks in May.
Marshalltown averages 132 frost days, 27 hot days (≥ 30 °C) and 106 rainy days per year.
Marshalltown has warmed by +1.8 °C between 1940 and 2025, or +0.22 °C per decade. This trend is statistically significant.
The number of frost days there went from about 140 to 124 per year over the period.
The hottest day of the period reached 38.2 °C (on 17 August 1988) and the coldest -34.0 °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
MarshalltownIowa
- coords
- 42.05°, -92.91°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
9.1°C
Average daily high
14.2°C
Average daily low
4.3°C
Annual rainfall
922mm
Sunshine / day
9.0h
Mean relative humidity
71%
Average peak wind
22.1km/h
Seasonal range
30.6°C
Frost days (< 0 °C)
132 d/yr
Hot days (≥ 30 °C)
27 d/yr
Rainy days (≥ 1 mm)
106 d/yr
Annual snowfall
70.3 cm
Average feels-like high
11.8 °C
Average feels-like low
1.0 °C
Average peak gust
40.2 km/h
Tropical nights (≥ 20 °C)
25 d/yr
Solar radiation
15.2 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.8 °C
since 1940
+0.2 °C per decade · r² = 0.29 · 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
38.2 °C
17 August 1988
Coldest day
-34.0 °C
3 February 1996
Wettest day
90 mm
7 June 1993
Windiest day
75.6 km/h
9 April 1973
Strongest gust
115.2 km/h
10 November 1998
Hottest feels-like
46.0 °C
6 July 1948
Coldest feels-like
-40.8 °C
3 February 1996
Snowiest day
32.8 cm
9 April 1973
Sunniest day
14.8 h
19 June 1940
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 | -1.0 °C | +2.0 °C | 12 mm | -21 mm |
| Feb | -1.1 °C | -0.7 °C | 13 mm | -22 mm |
| Mar | 13.7 °C | +6.9 °C | 115 mm | +44 mm |
| Apr | 16.2 °C | +1.1 °C | 107 mm | +4 mm |
| May | 22.1 °C | +0.8 °C | 56 mm | -67 mm |
| Jun | 28.3 °C | +1.9 °C | 131 mm | +11 mm |
| Jul | 28.4 °C | +0.2 °C | 237 mm | +140 mm |
| Aug | 26.5 °C | -0.7 °C | 44 mm | -53 mm |
| Sep | 26.1 °C | +2.7 °C | 52 mm | -34 mm |
| Oct | 19.5 °C | +2.5 °C | 59 mm | -8 mm |
| Nov | 9.4 °C | +1.6 °C | 45 mm | -7 mm |
| Dec | 0.2 °C | +0.1 °C | 28 mm | -9 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 Marshalltown?
Marshalltown has a hot-summer humid continental climate (Köppen Dfa). Over 1940-2025, the average annual temperature is 9.1 °C and it receives 922 mm of precipitation per year.
What is the hottest day ever recorded in Marshalltown?
The hottest day measured in Marshalltown between 1940 and 2025 was 17 August 1988, reaching 38.2 °C.
What is the coldest day in Marshalltown?
The coldest day measured in Marshalltown between 1940 and 2025 was 3 February 1996, at -34.0 °C.
Does it snow in Marshalltown?
Yes. Marshalltown gets on average 70.3 cm of snow per year and has around 132 frost days.
Has the climate of Marshalltown warmed?
Yes: Marshalltown warmed by +1.8 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Marshalltown?
The wettest day measured in Marshalltown between 1940 and 2025 was 7 June 1993, with 90 mm of rain in 24 hours.
What was the windiest day in Marshalltown?
The windiest day measured in Marshalltown between 1940 and 2025 was 9 April 1973, with winds reaching 75.6 km/h.
What is the warmest month in Marshalltown?
The warmest month in Marshalltown is July (23.2 °C on average); the coldest is January (-7.4 °C).
How much does it rain in Marshalltown?
Marshalltown receives on average 922 mm of precipitation per year, spread over about 106 rainy days.
Is it sunny in Marshalltown?
Marshalltown gets on average 9.0 hours of sunshine per day, roughly 3,285 hours per year over 1940-2025.
What is the biggest single-day snowfall in Marshalltown?
The heaviest 24-hour snowfall measured in Marshalltown between 1940 and 2025 was 9 April 1973, with 32.8 cm.
Are there tropical nights in Marshalltown?
Yes: Marshalltown has on average 25 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Marshalltown?
In Marshalltown, between 1940 and 2025, the highest apparent temperature reached 46.0 °C on 6 July 1948, and the lowest was -40.8 °C on 3 February 1996.
Compare Marshalltown with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Marshalltown