Rialto climate — normals and trends
Rialto (United States) has a hot-summer mediterranean climate (Csa) under the Köppen-Geiger classification. Its mean annual temperature is 15.7 °C and it receives 407 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 (24.0 °C on average) and the coldest is January (8.8 °C). Rainfall peaks in February.
Rialto averages 9 frost days, 71 hot days (≥ 30 °C) and 46 rainy days per year.
Rialto 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 18 to 0 per year over the period.
The hottest day of the period reached 43.8 °C (on 6 September 2020) and the coldest -9.6 °C (on 12 January 1949).
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
RialtoCalifornia
- coords
- 34.11°, -117.37°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
15.7°C
Average daily high
22.4°C
Average daily low
10.3°C
Annual rainfall
407mm
Sunshine / day
11.3h
Mean relative humidity
55%
Average peak wind
11.1km/h
Seasonal range
15.2°C
Frost days (< 0 °C)
9 d/yr
Hot days (≥ 30 °C)
71 d/yr
Rainy days (≥ 1 mm)
46 d/yr
Annual snowfall
11.0 cm
Average feels-like high
21.2 °C
Average feels-like low
8.4 °C
Average peak gust
31.5 km/h
Tropical nights (≥ 20 °C)
18 d/yr
Solar radiation
20.5 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+2.3 °C
since 1940
+0.3 °C per decade · r² = 0.59 · 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
43.8 °C
6 September 2020
Coldest day
-9.6 °C
12 January 1949
Wettest day
87 mm
25 January 1969
Windiest day
30.3 km/h
30 November 1982
Strongest gust
93.2 km/h
30 November 1982
Hottest feels-like
43.0 °C
6 July 2018
Coldest feels-like
-14.3 °C
12 January 1949
Snowiest day
16.8 cm
31 January 1979
Sunniest day
14.0 h
12 June 1940
Normals computed over complete calendar years 1940–2025.
A specific year
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Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | 16.4 °C | +1.5 °C | 17 mm | -54 mm |
| Feb | 18.8 °C | +3.2 °C | 81 mm | +1 mm |
| Mar | 16.8 °C | -0.1 °C | 81 mm | +16 mm |
| Apr | 20.3 °C | +0.4 °C | 17 mm | -16 mm |
| May | 24.8 °C | +1.7 °C | 12 mm | +0 mm |
| Jun | 29.0 °C | +1.4 °C | 3 mm | +0 mm |
| Jul | 30.5 °C | -0.7 °C | 3 mm | -7 mm |
| Aug | 32.9 °C | +1.8 °C | 7 mm | -6 mm |
| Sep | 28.7 °C | -0.5 °C | 28 mm | +17 mm |
| Oct | 25.2 °C | +0.8 °C | 33 mm | +16 mm |
| Nov | 20.8 °C | +1.7 °C | 116 mm | +79 mm |
| Dec | 19.7 °C | +4.2 °C | 80 mm | +24 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 Rialto?
Rialto has a hot-summer mediterranean climate (Köppen Csa). Over 1940-2025, the average annual temperature is 15.7 °C and it receives 407 mm of precipitation per year.
What is the hottest day ever recorded in Rialto?
The hottest day measured in Rialto between 1940 and 2025 was 6 September 2020, reaching 43.8 °C.
What is the coldest day in Rialto?
The coldest day measured in Rialto between 1940 and 2025 was 12 January 1949, at -9.6 °C.
Does it snow in Rialto?
Yes. Rialto gets on average 11.0 cm of snow per year and has around 9 frost days.
Has the climate of Rialto warmed?
Yes: Rialto warmed by +2.3 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Rialto?
The wettest day measured in Rialto between 1940 and 2025 was 25 January 1969, with 87 mm of rain in 24 hours.
What was the windiest day in Rialto?
The windiest day measured in Rialto between 1940 and 2025 was 30 November 1982, with winds reaching 30.3 km/h.
What is the warmest month in Rialto?
The warmest month in Rialto is July (24.0 °C on average); the coldest is January (8.8 °C).
How much does it rain in Rialto?
Rialto receives on average 407 mm of precipitation per year, spread over about 46 rainy days.
Is it sunny in Rialto?
Rialto gets on average 11.3 hours of sunshine per day, roughly 4,125 hours per year over 1940-2025.
What is the biggest single-day snowfall in Rialto?
The heaviest 24-hour snowfall measured in Rialto between 1940 and 2025 was 31 January 1979, with 16.8 cm.
Are there tropical nights in Rialto?
Yes: Rialto has on average 18 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Rialto?
In Rialto, between 1940 and 2025, the highest apparent temperature reached 43.0 °C on 6 July 2018, and the lowest was -14.3 °C on 12 January 1949.
Compare Rialto with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Rialto