Naperville climate — normals and trends
Naperville (United States) has a hot-summer humid continental climate (Dfa) under the Köppen-Geiger classification. Its mean annual temperature is 9.7 °C and it receives 917 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 (23.1 °C on average) and the coldest is January (-5.3 °C). Rainfall peaks in April.
Naperville averages 122 frost days, 25 hot days (≥ 30 °C) and 115 rainy days per year.
Naperville 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 135 to 109 per year over the period.
The hottest day of the period reached 38.4 °C (on 25 June 1988) and the coldest -34.3 °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
NapervilleIllinois
- coords
- 41.79°, -88.15°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
9.7°C
Average daily high
14.5°C
Average daily low
5.0°C
Annual rainfall
917mm
Sunshine / day
8.5h
Mean relative humidity
71%
Average peak wind
19.0km/h
Seasonal range
28.4°C
Frost days (< 0 °C)
122 d/yr
Hot days (≥ 30 °C)
25 d/yr
Rainy days (≥ 1 mm)
115 d/yr
Annual snowfall
69.6 cm
Average feels-like high
12.6 °C
Average feels-like low
2.2 °C
Average peak gust
38.8 km/h
Tropical nights (≥ 20 °C)
25 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 = 0.39 · 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
38.4 °C
25 June 1988
Coldest day
-34.3 °C
31 January 2019
Wettest day
100 mm
25 June 2021
Windiest day
51.7 km/h
11 November 1940
Strongest gust
112.0 km/h
10 November 1998
Hottest feels-like
43.9 °C
14 July 1995
Coldest feels-like
-39.4 °C
31 January 2019
Snowiest day
23.7 cm
1 December 2006
Sunniest day
14.4 h
15 June 1955
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 | -1.1 °C | +0.3 °C | 33 mm | -18 mm |
| Feb | 1.4 °C | +0.3 °C | 20 mm | -26 mm |
| Mar | 12.8 °C | +5.3 °C | 101 mm | +27 mm |
| Apr | 16.0 °C | +1.3 °C | 69 mm | -32 mm |
| May | 20.1 °C | -0.6 °C | 102 mm | +1 mm |
| Jun | 28.5 °C | +2.4 °C | 118 mm | +18 mm |
| Jul | 29.3 °C | +1.2 °C | 122 mm | +34 mm |
| Aug | 26.9 °C | -0.3 °C | 98 mm | +14 mm |
| Sep | 25.7 °C | +2.3 °C | 45 mm | -30 mm |
| Oct | 18.8 °C | +1.9 °C | 66 mm | -6 mm |
| Nov | 9.5 °C | +1.1 °C | 50 mm | -16 mm |
| Dec | 0.8 °C | -0.6 °C | 68 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 Naperville?
Naperville has a hot-summer humid continental climate (Köppen Dfa). Over 1940-2025, the average annual temperature is 9.7 °C and it receives 917 mm of precipitation per year.
What is the hottest day ever recorded in Naperville?
The hottest day measured in Naperville between 1940 and 2025 was 25 June 1988, reaching 38.4 °C.
What is the coldest day in Naperville?
The coldest day measured in Naperville between 1940 and 2025 was 31 January 2019, at -34.3 °C.
Does it snow in Naperville?
Yes. Naperville gets on average 69.6 cm of snow per year and has around 122 frost days.
Has the climate of Naperville warmed?
Yes: Naperville warmed by +2.1 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Naperville?
The wettest day measured in Naperville between 1940 and 2025 was 25 June 2021, with 100 mm of rain in 24 hours.
What was the windiest day in Naperville?
The windiest day measured in Naperville between 1940 and 2025 was 11 November 1940, with winds reaching 51.7 km/h.
What is the warmest month in Naperville?
The warmest month in Naperville is July (23.1 °C on average); the coldest is January (-5.3 °C).
How much does it rain in Naperville?
Naperville receives on average 917 mm of precipitation per year, spread over about 115 rainy days.
Is it sunny in Naperville?
Naperville gets on average 8.5 hours of sunshine per day, roughly 3,103 hours per year over 1940-2025.
What is the biggest single-day snowfall in Naperville?
The heaviest 24-hour snowfall measured in Naperville between 1940 and 2025 was 1 December 2006, with 23.7 cm.
Are there tropical nights in Naperville?
Yes: Naperville has on average 25 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Naperville?
In Naperville, between 1940 and 2025, the highest apparent temperature reached 43.9 °C on 14 July 1995, and the lowest was -39.4 °C on 31 January 2019.
Compare Naperville with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Naperville