Patterson climate — normals and trends
Patterson (United States) has a hot-summer mediterranean climate (Csa) under the Köppen-Geiger classification. Its mean annual temperature is 16.3 °C and it receives 402 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 (25.2 °C on average) and the coldest is January (8.3 °C). Rainfall peaks in January.
Patterson averages 6 frost days, 95 hot days (≥ 30 °C) and 52 rainy days per year.
Patterson has warmed by +2.3 °C between 1940 and 2025, or +0.27 °C per decade. This trend is statistically significant.
The number of frost days there went from about 10 to 2 per year over the period.
The hottest day of the period reached 46.0 °C (on 6 September 2022) and the coldest -6.7 °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
PattersonCalifornia
- coords
- 37.47°, -121.13°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
16.3°C
Average daily high
22.9°C
Average daily low
10.5°C
Annual rainfall
402mm
Sunshine / day
10.8h
Mean relative humidity
56%
Average peak wind
12.5km/h
Seasonal range
16.9°C
Frost days (< 0 °C)
6 d/yr
Hot days (≥ 30 °C)
95 d/yr
Rainy days (≥ 1 mm)
52 d/yr
Annual snowfall
1.1 cm
Average feels-like high
21.7 °C
Average feels-like low
8.3 °C
Average peak gust
30.1 km/h
Tropical nights (≥ 20 °C)
12 d/yr
Solar radiation
19.4 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+2.3 °C
since 1940
+0.3 °C per decade · r² = 0.61 · 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
46.0 °C
6 September 2022
Coldest day
-6.7 °C
22 December 1990
Wettest day
70 mm
13 October 2009
Windiest day
38.6 km/h
29 October 1959
Strongest gust
101.5 km/h
14 February 1986
Hottest feels-like
46.0 °C
13 July 1990
Coldest feels-like
-11.4 °C
22 December 1990
Snowiest day
6.7 cm
4 January 1974
Sunniest day
14.1 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 | 15.5 °C | +2.4 °C | 15 mm | -59 mm |
| Feb | 16.8 °C | +1.6 °C | 82 mm | +10 mm |
| Mar | 18.3 °C | +0.8 °C | 66 mm | +1 mm |
| Apr | 24.1 °C | +2.9 °C | 19 mm | -14 mm |
| May | 29.3 °C | +3.5 °C | 1 mm | -14 mm |
| Jun | 33.3 °C | +3.1 °C | 0 mm | -4 mm |
| Jul | 34.5 °C | +0.9 °C | 0 mm | -1 mm |
| Aug | 35.5 °C | +2.9 °C | 0 mm | -2 mm |
| Sep | 31.8 °C | +1.8 °C | 4 mm | -2 mm |
| Oct | 23.9 °C | -0.6 °C | 48 mm | +27 mm |
| Nov | 18.4 °C | +0.8 °C | 87 mm | +43 mm |
| Dec | 13.9 °C | +0.6 °C | 60 mm | -5 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 Patterson?
Patterson has a hot-summer mediterranean climate (Köppen Csa). Over 1940-2025, the average annual temperature is 16.3 °C and it receives 402 mm of precipitation per year.
What is the hottest day ever recorded in Patterson?
The hottest day measured in Patterson between 1940 and 2025 was 6 September 2022, reaching 46.0 °C.
What is the coldest day in Patterson?
The coldest day measured in Patterson between 1940 and 2025 was 22 December 1990, at -6.7 °C.
Does it snow in Patterson?
Yes. Patterson gets on average 1.1 cm of snow per year and has around 6 frost days.
Has the climate of Patterson warmed?
Yes: Patterson warmed by +2.3 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Patterson?
The wettest day measured in Patterson between 1940 and 2025 was 13 October 2009, with 70 mm of rain in 24 hours.
What was the windiest day in Patterson?
The windiest day measured in Patterson between 1940 and 2025 was 29 October 1959, with winds reaching 38.6 km/h.
What is the warmest month in Patterson?
The warmest month in Patterson is July (25.2 °C on average); the coldest is January (8.3 °C).
How much does it rain in Patterson?
Patterson receives on average 402 mm of precipitation per year, spread over about 52 rainy days.
Is it sunny in Patterson?
Patterson gets on average 10.8 hours of sunshine per day, roughly 3,942 hours per year over 1940-2025.
What is the biggest single-day snowfall in Patterson?
The heaviest 24-hour snowfall measured in Patterson between 1940 and 2025 was 4 January 1974, with 6.7 cm.
Are there tropical nights in Patterson?
Yes: Patterson has on average 12 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Patterson?
In Patterson, between 1940 and 2025, the highest apparent temperature reached 46.0 °C on 13 July 1990, and the lowest was -11.4 °C on 22 December 1990.
Compare Patterson with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Patterson