Atwater climate — normals and trends
Atwater (United States) has a hot-summer mediterranean climate (Csa) under the Köppen-Geiger classification. Its mean annual temperature is 17.5 °C and it receives 422 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 (27.3 °C on average) and the coldest is January (8.5 °C). Rainfall peaks in January.
Atwater averages 7 frost days, 117 hot days (≥ 30 °C) and 47 rainy days per year.
Atwater has warmed by +2.9 °C between 1940 and 2025, or +0.34 °C per decade. This trend is statistically significant.
The number of frost days there went from about 13 to 1 per year over the period.
The hottest day of the period reached 47.3 °C (on 6 September 2022) and the coldest -6.8 °C (on 22 December 1990).
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
AtwaterCalifornia
- coords
- 37.35°, -120.61°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
17.5°C
Average daily high
24.4°C
Average daily low
11.4°C
Annual rainfall
422mm
Sunshine / day
11.0h
Mean relative humidity
57%
Average peak wind
13.2km/h
Seasonal range
18.8°C
Frost days (< 0 °C)
7 d/yr
Hot days (≥ 30 °C)
117 d/yr
Rainy days (≥ 1 mm)
47 d/yr
Annual snowfall
0.1 cm
Average feels-like high
23.4 °C
Average feels-like low
9.5 °C
Average peak gust
27.7 km/h
Tropical nights (≥ 20 °C)
29 d/yr
Solar radiation
19.6 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+2.9 °C
since 1940
+0.3 °C per decade · r² = 0.70 · 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
47.3 °C
6 September 2022
Coldest day
-6.8 °C
22 December 1990
Wettest day
81 mm
9 February 1962
Windiest day
43.0 km/h
4 January 1995
Strongest gust
88.9 km/h
10 March 1995
Hottest feels-like
48.4 °C
25 June 1995
Coldest feels-like
-11.4 °C
22 December 1990
Snowiest day
1.5 cm
27 December 1988
Sunniest day
14.0 h
6 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 | 17.0 °C | +3.1 °C | 9 mm | -71 mm |
| Feb | 18.9 °C | +2.5 °C | 100 mm | +25 mm |
| Mar | 20.3 °C | +1.3 °C | 85 mm | +13 mm |
| Apr | 26.3 °C | +3.4 °C | 14 mm | -20 mm |
| May | 31.9 °C | +4.1 °C | 1 mm | -13 mm |
| Jun | 36.2 °C | +3.8 °C | 0 mm | -3 mm |
| Jul | 37.6 °C | +1.9 °C | 0 mm | -1 mm |
| Aug | 38.4 °C | +3.8 °C | 1 mm | -0 mm |
| Sep | 34.4 °C | +2.8 °C | 5 mm | +0 mm |
| Oct | 26.2 °C | +0.4 °C | 33 mm | +13 mm |
| Nov | 19.6 °C | +1.0 °C | 113 mm | +66 mm |
| Dec | 14.2 °C | +0.2 °C | 78 mm | +8 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 Atwater?
Atwater has a hot-summer mediterranean climate (Köppen Csa). Over 1940-2025, the average annual temperature is 17.5 °C and it receives 422 mm of precipitation per year.
What is the hottest day ever recorded in Atwater?
The hottest day measured in Atwater between 1940 and 2025 was 6 September 2022, reaching 47.3 °C.
What is the coldest day in Atwater?
The coldest day measured in Atwater between 1940 and 2025 was 22 December 1990, at -6.8 °C.
Does it snow in Atwater?
Almost never: Atwater sees virtually no snow, with about 7 frost days per year.
Has the climate of Atwater warmed?
Yes: Atwater warmed by +2.9 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Atwater?
The wettest day measured in Atwater between 1940 and 2025 was 9 February 1962, with 81 mm of rain in 24 hours.
What was the windiest day in Atwater?
The windiest day measured in Atwater between 1940 and 2025 was 4 January 1995, with winds reaching 43.0 km/h.
What is the warmest month in Atwater?
The warmest month in Atwater is July (27.3 °C on average); the coldest is January (8.5 °C).
How much does it rain in Atwater?
Atwater receives on average 422 mm of precipitation per year, spread over about 47 rainy days.
Is it sunny in Atwater?
Atwater gets on average 11.0 hours of sunshine per day, roughly 4,015 hours per year over 1940-2025.
What is the biggest single-day snowfall in Atwater?
The heaviest 24-hour snowfall measured in Atwater between 1940 and 2025 was 27 December 1988, with 1.5 cm.
Are there tropical nights in Atwater?
Yes: Atwater has on average 29 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Atwater?
In Atwater, between 1940 and 2025, the highest apparent temperature reached 48.4 °C on 25 June 1995, and the lowest was -11.4 °C on 22 December 1990.
Compare Atwater with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Atwater