30-year climate normals

San Bernardino County Climate and Weather Averages

Hottest month — July

105.0°

average daily high. The coldest month is December, averaging a low of 35.0°F.

San Bernardino County gets 3.77" of precipitation a year, and 49% of it falls in Dec, Jan, Feb.

Temperature through the year

Each bar spans the average daily low to the average daily high for that month.

Month	Avg high	Avg low	Precip
January	61.4°	36.2°	0.57"
February	65.5°	40.1°	0.70"
March	72.6°	45.6°	0.43"
April	79.5°	51.3°	0.22"
May	88.9°	59.5°	0.05"
June	99.4°	67.9°	0.03"
July	105.0°	74.2°	0.28"
August	103.9°	73.1°	0.20"
September	96.3°	66.0°	0.17"
October	83.2°	54.4°	0.24"
November	69.6°	42.5°	0.32"
December	59.9°	35.0°	0.56"

Rainfall by month

San Bernardino County has a distinct wet season. 49% of the year's precipitation arrives in Dec, Jan, Feb.

January 0.57"

February 0.70"

March 0.43"

April 0.22"

May 0.05"

June 0.03"

July 0.28"

August 0.20"

September 0.17"

October 0.24"

November 0.32"

December 0.56"

Annual total 3.77"

What this climate costs you

Degree days measure how hard a building has to work to stay comfortable. They are the reason two identical houses have very different power bills, and they are the link between the weather here and what you pay every month.

Cooling degree days How much air conditioning the climate demands 3,129

Heating degree days How much heating the climate demands 2,019

Approximate annual cooling cost At 33.25¢/kWh, California average $1,040

Approximate annual electric heating cost Lower where heating is gas rather than electric $235

These are rough planning figures from degree days and the state electricity price, not a bill estimate. House size, insulation and fuel type move them a lot. See the full cost of owning a home in San Bernardino County, where electricity is one line of eight.

Common questions

What is the weather like in San Bernardino County?

San Bernardino County averages a high of 105.0°F in July and a low of 35.0°F in December. Annual precipitation is 3.77 inches, with essentially no snow.

When is the rainy season in San Bernardino County?

The wettest stretch is Dec, Jan, Feb, which accounts for 49% of the year's precipitation. That is a pronounced wet season rather than rain spread evenly through the year.

How hot does it get in San Bernardino County?

The average daily high in July, the hottest month, is 105.0°F. That drives 3,129 cooling degree days a year, which is what your air conditioning has to work against.

Does it snow in San Bernardino County?

Effectively no. Measurable snowfall is rare in San Bernardino County.

Sources

Temperature, precipitation and snowfall normals — NOAA National Centers for Environmental Information, 1991–2020 Monthly Climate Normals, station BARSTOW DAGGETT AP, CA US (USW00023161), 34.3 miles from the county centroid.
Heating and cooling degree days — NOAA, same station and period.
Electricity price — US Energy Information Administration, Electric Power Monthly Table 5.6.A, California residential average.
Wet-season share is the wettest three consecutive months as a percentage of annual precipitation, calculated from the monthly normals.