Ballwin climate — normals and trends
Ballwin (United States) has a hot-summer humid continental climate (Dfa) under the Köppen-Geiger classification. Its mean annual temperature is 13.3 °C and it receives 991 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 (25.9 °C on average) and the coldest is January (-0.7 °C). Rainfall peaks in May.
Ballwin averages 85 frost days, 62 hot days (≥ 30 °C) and 112 rainy days per year.
Ballwin has warmed by +1.3 °C between 1940 and 2025, or +0.16 °C per decade. This trend is statistically significant.
The number of frost days there went from about 96 to 74 per year over the period.
The hottest day of the period reached 43.9 °C (on 14 July 1954) and the coldest -27.3 °C (on 17 January 1982).
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
BallwinMissouri
- coords
- 38.60°, -90.55°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
13.3°C
Average daily high
18.5°C
Average daily low
8.6°C
Annual rainfall
991mm
Sunshine / day
9.2h
Mean relative humidity
68%
Average peak wind
16.1km/h
Seasonal range
26.6°C
Frost days (< 0 °C)
85 d/yr
Hot days (≥ 30 °C)
62 d/yr
Rainy days (≥ 1 mm)
112 d/yr
Annual snowfall
38.2 cm
Average feels-like high
17.4 °C
Average feels-like low
6.6 °C
Average peak gust
35.9 km/h
Tropical nights (≥ 20 °C)
61 d/yr
Solar radiation
15.6 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.3 °C
since 1940
+0.2 °C per decade · r² = 0.23 · 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
43.9 °C
14 July 1954
Coldest day
-27.3 °C
17 January 1982
Wettest day
96 mm
14 September 2008
Windiest day
45.7 km/h
5 April 1947
Strongest gust
106.6 km/h
18 January 1996
Hottest feels-like
45.7 °C
14 July 1954
Coldest feels-like
-33.9 °C
20 January 1985
Snowiest day
27.0 cm
31 January 1982
Sunniest day
14.0 h
14 July 2022
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 | 2.5 °C | -1.4 °C | 56 mm | -5 mm |
| Feb | 6.0 °C | -0.6 °C | 44 mm | -19 mm |
| Mar | 18.0 °C | +5.6 °C | 82 mm | -18 mm |
| Apr | 20.1 °C | +1.2 °C | 169 mm | +59 mm |
| May | 22.6 °C | -1.3 °C | 127 mm | +15 mm |
| Jun | 28.7 °C | -0.3 °C | 215 mm | +123 mm |
| Jul | 31.1 °C | 0.0 °C | 114 mm | +36 mm |
| Aug | 29.8 °C | -0.5 °C | 19 mm | -55 mm |
| Sep | 28.9 °C | +2.4 °C | 102 mm | +28 mm |
| Oct | 21.9 °C | +1.5 °C | 79 mm | -0 mm |
| Nov | 13.8 °C | +1.4 °C | 76 mm | -6 mm |
| Dec | 7.7 °C | +1.5 °C | 19 mm | -48 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 Ballwin?
Ballwin has a hot-summer humid continental climate (Köppen Dfa). Over 1940-2025, the average annual temperature is 13.3 °C and it receives 991 mm of precipitation per year.
What is the hottest day ever recorded in Ballwin?
The hottest day measured in Ballwin between 1940 and 2025 was 14 July 1954, reaching 43.9 °C.
What is the coldest day in Ballwin?
The coldest day measured in Ballwin between 1940 and 2025 was 17 January 1982, at -27.3 °C.
Does it snow in Ballwin?
Yes. Ballwin gets on average 38.2 cm of snow per year and has around 85 frost days.
Has the climate of Ballwin warmed?
Yes: Ballwin warmed by +1.3 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Ballwin?
The wettest day measured in Ballwin between 1940 and 2025 was 14 September 2008, with 96 mm of rain in 24 hours.
What was the windiest day in Ballwin?
The windiest day measured in Ballwin between 1940 and 2025 was 5 April 1947, with winds reaching 45.7 km/h.
What is the warmest month in Ballwin?
The warmest month in Ballwin is July (25.9 °C on average); the coldest is January (-0.7 °C).
How much does it rain in Ballwin?
Ballwin receives on average 991 mm of precipitation per year, spread over about 112 rainy days.
Is it sunny in Ballwin?
Ballwin gets on average 9.2 hours of sunshine per day, roughly 3,358 hours per year over 1940-2025.
What is the biggest single-day snowfall in Ballwin?
The heaviest 24-hour snowfall measured in Ballwin between 1940 and 2025 was 31 January 1982, with 27.0 cm.
Are there tropical nights in Ballwin?
Yes: Ballwin has on average 61 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Ballwin?
In Ballwin, between 1940 and 2025, the highest apparent temperature reached 45.7 °C on 14 July 1954, and the lowest was -33.9 °C on 20 January 1985.
Compare Ballwin with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Ballwin