Rancho Cucamonga, CA climate
Rancho Cucamonga has warm winters and hot summers, with very little rain. A typical July afternoon reaches 93°, a January night drops to 44°, and snow is almost unheard of.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Rancho Cucamonga feels like
Winter
Spring
Summer
Fall
Rancho Cucamonga weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 66° | 44° | 4.5" | 0 | 5 | 0 | 51° – 61° |
| February | 66° | 44° | 4.8" | 0 | 6 | 0 | 48° – 65° |
| March | 70° | 47° | 3.1" | 0 | 4 | 0 | 51° – 66° |
| April | 74° | 49° | 1.1" | 0 | 2 | 0 | 56° – 66° |
| May | 78° | 53° | 0.5" | 0 | 1 | 0 | 59° – 73° |
| June | 86° | 58° | 0.1" | 0 | 0 | 0 | 66° – 77° |
| July | 93° | 63° | 0.1" | 0 | 0 | 0 | 72° – 84° |
| August | 94° | 64° | 0.0" | 0 | 0 | 0 | 76° – 83° |
| September | 90° | 61° | 0.2" | 0 | 0 | 0 | 71° – 80° |
| October | 82° | 55° | 0.8" | 0 | 3 | 0 | 63° – 73° |
| November | 73° | 48° | 1.4" | 0 | 3 | 0 | 52° – 65° |
| December | 65° | 43° | 3.5" | 0 | 5 | 0 | 50° – 61° |
| Year | 78° | 52° | 20.0" | 0.0" | 31 | 0 |
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain and snow in Rancho Cucamonga
Rancho Cucamonga gets 20 inches of rain and melted snow a year. February is the wettest month and August the driest. Rain or snow falls on about 31 days a year.
A year-round growing season
Heating and cooling a home in Rancho Cucamonga
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Rancho Cucamonga, 40% of that work is heating and 60% is cooling, so air conditioning is the bigger bill.
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
Rancho Cucamonga and its neighbors
Rancho Cucamonga borders 4 towns with climate data. January nights across them vary by 2.7°. Fontana has both the coldest January nights (43°) and the hottest July afternoons (94°). Rancho Cucamonga’s January low is 44° and its July high 93°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Rancho Cucamonga compares
Compared with every U.S. town and city on TownTapestry, each counted once.
Warmer than it used to be
The last 30 years in Rancho Cucamonga averaged 2.5° warmer than the 1900s. The biggest change is in January (+3.4°). The shift is larger than in 100% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Rancho Cucamonga’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. February swings the most: between 1991 and 2020 its average temperature ranged from 48° to 65°. August is the most reliable, staying within 7°.
Common questions about Rancho Cucamonga’s climate
What is the coldest month in Rancho Cucamonga?
December, with a typical high of 65° and a low of 43°.
What is the hottest month in Rancho Cucamonga?
August, with a typical high of 94° and a low of 64°. About 93 days a year reach 90°.
How much snow does Rancho Cucamonga get?
Almost none. A normal year brings 0.0 inches.
When is the first frost in Rancho Cucamonga?
Frost is uncommon. Only 41% of years see a night at 32° or below.
What is the rainiest month in Rancho Cucamonga?
February, with 4.8 inches of rain and melted snow. The year totals 20 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Rancho Cucamonga itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Pomona/fairplex, CA (12 mi, snow) and Ontario Intl Airport, CA (5 mi, frost, heat and degree days). Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.