San Bernardino climate
San Bernardino (California, United States) has a hot semi-arid climate (Köppen BSh). The average temperature over the year is 19 °C67 °F, and about 289 mm11 in of precipitation falls in an average year.
Temperature by month
Precipitation by month
San Bernardino climate table
| Month | High °C°F | Low °C°F | Mean °C°F | Precip. mmin |
|---|---|---|---|---|
| Jan | 1966 | 643 | 1254 | 582.3 |
| Feb | 1967 | 644 | 1355 | 632.5 |
| Mar | 2272 | 847 | 1559 | 321.3 |
| Apr | 2476 | 1049 | 1763 | 180.7 |
| May | 2882 | 1254 | 2068 | 70.3 |
| Jun | 3290 | 1660 | 2475 | 10.0 |
| Jul | 3696 | 1967 | 2781 | 50.2 |
| Aug | 3696 | 2067 | 2882 | 30.1 |
| Sep | 3493 | 1865 | 2679 | 40.2 |
| Oct | 2983 | 1457 | 2170 | 150.6 |
| Nov | 2373 | 1049 | 1661 | 240.9 |
| Dec | 1865 | 643 | 1254 | 582.3 |
| Year | 3696 | 643 | 1967 | 28911 |
“Year” row: highest monthly high, lowest monthly low, annual mean and annual total.
| Month | Humid. | Cloud | Solar | Daylight |
|---|---|---|---|---|
| Jan | 55% | 44% | 3.3 | 10:07 |
| Feb | 59% | 40% | 4.2 | 10:55 |
| Mar | 59% | 35% | 5.6 | 11:53 |
| Apr | 57% | 30% | 6.9 | 12:00 |
| May | 55% | 23% | 7.8 | 13:55 |
| Jun | 47% | 15% | 8.4 | 14:25 |
| Jul | 41% | 20% | 7.9 | 14:13 |
| Aug | 38% | 16% | 7.4 | 13:25 |
| Sep | 40% | 14% | 6.3 | 12:20 |
| Oct | 45% | 23% | 4.9 | 11:16 |
| Nov | 47% | 33% | 3.7 | 10:20 |
| Dec | 54% | 43% | 2.9 | 9:53 |
Humid. = average relative humidity at 2 m; cloud = average cloud amount; solar = average daily solar energy reaching the ground in kWh/m² (all-sky); daylight in hours:minutes, calculated for the 15th of each month.
What the climate of San Bernardino is like
The warmest month is August, with an average high of 36 °C96 °F and a low of 20 °C67 °F. The coldest is December, when highs average 18 °C65 °F and lows 6 °C43 °F. There is a clear seasonal cycle, with 15.7 °C28.3 °F between the average temperature of the warmest and the coolest month.
It is dry, with about 289 mm11 in of precipitation per year. The wettest three-month stretch is December–February, which brings 62% of the annual total. Months with less than 20 mm0.8 in on average: April–October. The wettest month is February (63 mm2.5 in), the driest is June (1 mm0.0 in).
Relative humidity ranges from 38% in August to 59% in February. The clearest skies (lowest average cloud amount, 14%) are typical of September. Average wind speed near the ground ranges from 6 km/h (4 mph) in September to 7 km/h (4 mph) in April. Daylight lasts from about 9.9 hours in December to 14.4 hours in June.
Best time to visit San Bernardino
Based on these averages, the most comfortable months for sightseeing and outdoor activities are October–May: average highs of 18 °C65 °F to 29 °C83 °F with 7 mm0.3 in to 63 mm2.5 in of precipitation per month.
The most challenging month is August, which is hot, with average highs of 36 °C96 °F.
Comfort score: months are ranked by how close they come to an average high of 21–28 °C (70–82 °F), lows above 5 °C (41 °F), little precipitation and moderate humidity. The best-ranked months of each place are recommended, even where none meets all of these. These are general rules of thumb applied to long-term averages.
What to pack for San Bernardino
- Winter (December–February) — highs 1865 to 19 °C67 °F, lows around 6 °C43 °F, about 60 mm2.3 in of precipitation a month. Pack light layers — T-shirts plus a light sweater or jacket and an extra layer for the cooler mornings and evenings.
- Spring (March–May) — highs 2272 to 28 °C82 °F, lows 847 to 12 °C54 °F, about 19 mm0.8 in of precipitation a month. Pack light summer clothes such as T-shirts, shorts or light dresses and an extra layer for the cooler mornings and evenings.
- Summer (June–August) — highs 3290 to 36 °C96 °F, lows 1660 to 20 °C67 °F, about 3 mm0.1 in of precipitation a month. Pack very light, breathable clothing, a sun hat and plenty of water.
- Autumn (September–November) — highs 2373 to 34 °C93 °F, lows 1049 to 18 °C65 °F, about 15 mm0.6 in of precipitation a month. Pack light summer clothes such as T-shirts, shorts or light dresses and an extra layer for the cooler mornings and evenings.
How San Bernardino compares
Compared with Riverside, about 20 km to the southwest, San Bernardino is on average 0.4 °C0.8 °F cooler and receives a similar amount of precipitation.
Of the 222 places in the United States covered by World Climates, San Bernardino is the 45th warmest by annual mean temperature and the 208th wettest by annual precipitation. See all of them on the United States climate page.
Places in other countries with the most similar temperature and rainfall pattern (seasons shifted for the other hemisphere where needed): Beersheba (Israel, BSh), Santiago (Chile, BSh) and Irákleion (Greece, Csa).
The same NASA POWER grid cell also contains Fontana (pop. 212,704), Rancho Cucamonga (pop. 175,236), Ontario (pop. 171,214), Pomona (pop. 153,266) and Rialto (pop. 103,132). Their long-term averages in this dataset are essentially the same as for San Bernardino, so they do not have separate pages.
Nearby places
- Riverside 20 km · 20 °C68 °F · 289 mm11 in
- Victorville 48 km · 17 °C63 °F · 235 mm9.3 in
- West Covina 60 km · 19 °C67 °F · 331 mm13 in
- Murrieta 62 km · 17 °C63 °F · 298 mm12 in
- Anaheim 65 km · 20 °C67 °F · 331 mm13 in
- Santa Ana 67 km · 17 °C63 °F · 311 mm12 in
- Temecula 70 km · 20 °C68 °F · 299 mm12 in
- Los Angeles 88 km · 19 °C67 °F · 331 mm13 in
Frequently asked questions
What is the warmest month in San Bernardino?
August is the warmest month in San Bernardino, with an average high of 36 °C (96 °F) and an average low of 20 °C (67 °F).
What is the coldest month in San Bernardino?
December is the coldest month, with an average high of 18 °C (65 °F) and an average low of 6 °C (43 °F).
When does it rain the most in San Bernardino?
February is the wettest month with about 63 mm (2.5 in) of precipitation; June is the driest with about 1 mm (0.0 in).
What is the best time to visit San Bernardino?
Judging by long-term averages, the most comfortable months are October–May.
About this data
All figures are 25-year averages (January 2001 – December 2025) from the NASA POWER project. Temperature, humidity, wind and precipitation come from the MERRA-2 reanalysis (precipitation is the bias-corrected MERRA-2 product), cloud and solar values from CERES satellite data. They describe a grid cell of roughly 50–70 km, not a single weather station, so they can differ from airport records — most of all on coasts, in mountains and for rainfall. Average highs and lows are the monthly mean temperature plus/minus half of the average daily temperature range. Counts of rainy days are not part of this dataset.
The grid cell’s average elevation is 628 m, while San Bernardino lies at about 321 m. Temperatures on this page were therefore adjusted by +2 °C3.6 °F using the standard lapse rate of 6.5 °C per 1,000 m.