Castaic climate — normals and trends
Castaic (United States) has a hot-summer mediterranean climate (Csa) under the Köppen-Geiger classification. Its mean annual temperature is 15.9 °C and it receives 348 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 (24.1 °C on average) and the coldest is January (8.5 °C). Rainfall peaks in February.
Castaic averages 10 frost days, 71 hot days (≥ 30 °C) and 39 rainy days per year.
Castaic has warmed by +2.1 °C between 1940 and 2025, or +0.25 °C per decade. This trend is statistically significant.
The number of frost days there went from about 19 to 1 per year over the period.
The hottest day of the period reached 43.2 °C (on 6 September 2020) and the coldest -8.9 °C (on 3 March 1951).
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
CastaicCalifornia
- coords
- 34.49°, -118.62°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
15.9°C
Average daily high
22.5°C
Average daily low
10.3°C
Annual rainfall
348mm
Sunshine / day
11.3h
Mean relative humidity
55%
Average peak wind
14.9km/h
Seasonal range
15.6°C
Frost days (< 0 °C)
10 d/yr
Hot days (≥ 30 °C)
71 d/yr
Rainy days (≥ 1 mm)
39 d/yr
Annual snowfall
5.0 cm
Average feels-like high
20.8 °C
Average feels-like low
8.5 °C
Average peak gust
38.0 km/h
Tropical nights (≥ 20 °C)
17 d/yr
Solar radiation
20.9 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+2.1 °C
since 1940
+0.3 °C per decade · r² = 0.54 · 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
43.2 °C
6 September 2020
Coldest day
-8.9 °C
3 March 1951
Wettest day
90 mm
10 February 1962
Windiest day
40.3 km/h
19 January 2021
Strongest gust
95.0 km/h
21 November 1957
Hottest feels-like
43.7 °C
6 September 2020
Coldest feels-like
-13.5 °C
3 March 1951
Snowiest day
28.4 cm
4 January 1974
Sunniest day
14.0 h
31 May 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 | 15.7 °C | +1.3 °C | 21 mm | -44 mm |
| Feb | 18.4 °C | +2.8 °C | 72 mm | -3 mm |
| Mar | 17.2 °C | -0.3 °C | 63 mm | +3 mm |
| Apr | 20.4 °C | -0.3 °C | 13 mm | -14 mm |
| May | 24.5 °C | +0.6 °C | 10 mm | +0 mm |
| Jun | 28.2 °C | +0.4 °C | 1 mm | -1 mm |
| Jul | 29.0 °C | -2.2 °C | 0 mm | -1 mm |
| Aug | 31.6 °C | +0.4 °C | 1 mm | -2 mm |
| Sep | 28.1 °C | -1.2 °C | 36 mm | +28 mm |
| Oct | 24.0 °C | -0.6 °C | 54 mm | +40 mm |
| Nov | 19.5 °C | +0.7 °C | 119 mm | +88 mm |
| Dec | 18.2 °C | +3.3 °C | 133 mm | +82 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 Castaic?
Castaic has a hot-summer mediterranean climate (Köppen Csa). Over 1940-2025, the average annual temperature is 15.9 °C and it receives 348 mm of precipitation per year.
What is the hottest day ever recorded in Castaic?
The hottest day measured in Castaic between 1940 and 2025 was 6 September 2020, reaching 43.2 °C.
What is the coldest day in Castaic?
The coldest day measured in Castaic between 1940 and 2025 was 3 March 1951, at -8.9 °C.
Does it snow in Castaic?
Yes. Castaic gets on average 5.0 cm of snow per year and has around 10 frost days.
Has the climate of Castaic warmed?
Yes: Castaic warmed by +2.1 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Castaic?
The wettest day measured in Castaic between 1940 and 2025 was 10 February 1962, with 90 mm of rain in 24 hours.
What was the windiest day in Castaic?
The windiest day measured in Castaic between 1940 and 2025 was 19 January 2021, with winds reaching 40.3 km/h.
What is the warmest month in Castaic?
The warmest month in Castaic is July (24.1 °C on average); the coldest is January (8.5 °C).
How much does it rain in Castaic?
Castaic receives on average 348 mm of precipitation per year, spread over about 39 rainy days.
Is it sunny in Castaic?
Castaic 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 Castaic?
The heaviest 24-hour snowfall measured in Castaic between 1940 and 2025 was 4 January 1974, with 28.4 cm.
Are there tropical nights in Castaic?
Yes: Castaic has on average 17 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Castaic?
In Castaic, between 1940 and 2025, the highest apparent temperature reached 43.7 °C on 6 September 2020, and the lowest was -13.5 °C on 3 March 1951.
Compare Castaic with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Castaic