DeKalb climate — normals and trends
DeKalb (United States) has a hot-summer humid continental climate (Dfa) under the Köppen-Geiger classification. Its mean annual temperature is 9.2 °C and it receives 908 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 (22.7 °C on average) and the coldest is January (-6.2 °C). Rainfall peaks in May.
DeKalb averages 127 frost days, 21 hot days (≥ 30 °C) and 114 rainy days per year.
DeKalb has warmed by +2.1 °C between 1940 and 2025, or +0.24 °C per decade. This trend is statistically significant.
The number of frost days there went from about 139 to 115 per year over the period.
The hottest day of the period reached 38.1 °C (on 1 August 1988) and the coldest -34.1 °C (on 31 January 2019).
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
DeKalbIllinois
- coords
- 41.93°, -88.75°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
9.2°C
Average daily high
14.0°C
Average daily low
4.6°C
Annual rainfall
908mm
Sunshine / day
8.7h
Mean relative humidity
71%
Average peak wind
20.4km/h
Seasonal range
28.9°C
Frost days (< 0 °C)
127 d/yr
Hot days (≥ 30 °C)
21 d/yr
Rainy days (≥ 1 mm)
114 d/yr
Annual snowfall
74.4 cm
Average feels-like high
11.8 °C
Average feels-like low
1.4 °C
Average peak gust
38.9 km/h
Tropical nights (≥ 20 °C)
22 d/yr
Solar radiation
14.8 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+2.1 °C
since 1940
+0.2 °C per decade · r² = 0.37 · 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
38.1 °C
1 August 1988
Coldest day
-34.1 °C
31 January 2019
Wettest day
82 mm
13 September 2008
Windiest day
55.2 km/h
30 April 1984
Strongest gust
114.8 km/h
10 November 1998
Hottest feels-like
42.9 °C
13 July 1995
Coldest feels-like
-39.5 °C
31 January 2019
Snowiest day
21.9 cm
15 December 1987
Sunniest day
14.5 h
13 June 2021
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 | -1.7 °C | +0.6 °C | 36 mm | -12 mm |
| Feb | 0.2 °C | +0.1 °C | 22 mm | -21 mm |
| Mar | 12.4 °C | +5.5 °C | 100 mm | +27 mm |
| Apr | 15.7 °C | +1.3 °C | 87 mm | -14 mm |
| May | 20.3 °C | -0.3 °C | 84 mm | -19 mm |
| Jun | 28.3 °C | +2.5 °C | 102 mm | +2 mm |
| Jul | 28.9 °C | +1.3 °C | 129 mm | +41 mm |
| Aug | 26.3 °C | -0.4 °C | 106 mm | +22 mm |
| Sep | 25.4 °C | +2.3 °C | 78 mm | -3 mm |
| Oct | 18.6 °C | +2.1 °C | 42 mm | -30 mm |
| Nov | 9.1 °C | +1.2 °C | 54 mm | -9 mm |
| Dec | 0.1 °C | -0.5 °C | 64 mm | +10 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 DeKalb?
DeKalb has a hot-summer humid continental climate (Köppen Dfa). Over 1940-2025, the average annual temperature is 9.2 °C and it receives 908 mm of precipitation per year.
What is the hottest day ever recorded in DeKalb?
The hottest day measured in DeKalb between 1940 and 2025 was 1 August 1988, reaching 38.1 °C.
What is the coldest day in DeKalb?
The coldest day measured in DeKalb between 1940 and 2025 was 31 January 2019, at -34.1 °C.
Does it snow in DeKalb?
Yes. DeKalb gets on average 74.4 cm of snow per year and has around 127 frost days.
Has the climate of DeKalb warmed?
Yes: DeKalb warmed by +2.1 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in DeKalb?
The wettest day measured in DeKalb between 1940 and 2025 was 13 September 2008, with 82 mm of rain in 24 hours.
What was the windiest day in DeKalb?
The windiest day measured in DeKalb between 1940 and 2025 was 30 April 1984, with winds reaching 55.2 km/h.
What is the warmest month in DeKalb?
The warmest month in DeKalb is July (22.7 °C on average); the coldest is January (-6.2 °C).
How much does it rain in DeKalb?
DeKalb receives on average 908 mm of precipitation per year, spread over about 114 rainy days.
Is it sunny in DeKalb?
DeKalb gets on average 8.7 hours of sunshine per day, roughly 3,175 hours per year over 1940-2025.
What is the biggest single-day snowfall in DeKalb?
The heaviest 24-hour snowfall measured in DeKalb between 1940 and 2025 was 15 December 1987, with 21.9 cm.
Are there tropical nights in DeKalb?
Yes: DeKalb has on average 22 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in DeKalb?
In DeKalb, between 1940 and 2025, the highest apparent temperature reached 42.9 °C on 13 July 1995, and the lowest was -39.5 °C on 31 January 2019.
Compare DeKalb with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around DeKalb