Rosemont, CA climate
Rosemont has mild winters and hot summers, with very little rain. A typical July afternoon reaches 94°, a January night drops to 39°, and snow is almost unheard of.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Rosemont feels like
Winter
Spring
Summer
Fall
Rosemont 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 | 30-yr range |
|---|---|---|---|---|---|---|
| January | 56° | 39° | 4.0" | 0 | 11 | 43° – 52° |
| February | 62° | 42° | 3.8" | 0 | 10 | 48° – 56° |
| March | 67° | 45° | 2.9" | 0 | 9 | 50° – 62° |
| April | 73° | 47° | 1.6" | 0 | 5 | 54° – 64° |
| May | 81° | 52° | 1.2" | 0 | 4 | 60° – 74° |
| June | 89° | 58° | 0.2" | 0 | 1 | 68° – 77° |
| July | 94° | 61° | 0.0" | 0 | 0 | 74° – 81° |
| August | 94° | 60° | 0.0" | 0 | 0 | 73° – 82° |
| September | 90° | 58° | 0.1" | 0 | 1 | 70° – 77° |
| October | 79° | 51° | 0.9" | 0 | 3 | 62° – 70° |
| November | 66° | 44° | 1.8" | 0 | 7 | 48° – 60° |
| December | 57° | 39° | 3.3" | 0 | 10 | 44° – 53° |
| Year | 76° | 50° | 19.8" | 0.0" | 61 |
“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 Rosemont
Rosemont gets 20 inches of rain and melted snow a year. January is the wettest month and July the driest. Rain or snow falls on about 61 days a year.
A year-round growing season
Heating and cooling a home in Rosemont
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Rosemont, 58% of that work is heating and 42% is cooling.
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.
Rosemont and its neighbors
Rosemont borders 3 towns with climate data. January nights across them vary by 0.1°. Mather has both the coldest January nights (39°) and the hottest July afternoons (95°). Rosemont’s January low is 39° and its July high 94°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Rosemont 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 Rosemont averaged 1.3° warmer than the 1900s. The biggest change is in January (+1.8°). The shift is larger than in 55% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Rosemont’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. May swings the most: between 1991 and 2020 its average temperature ranged from 60° to 74°. September is the most reliable, staying within 7°.
Common questions about Rosemont’s climate
What is the coldest month in Rosemont?
December, with a typical high of 57° and a low of 39°.
What is the hottest month in Rosemont?
July, with a typical high of 94° and a low of 61°. About 90 days a year reach 90°.
How much snow does Rosemont get?
Almost none. A normal year brings 0.0 inches.
When is the first frost in Rosemont?
Frost is uncommon. Only 81% of years see a night at 32° or below.
What is the rainiest month in Rosemont?
January, with 4.0 inches of rain and melted snow. The year totals 20 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Rosemont itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Sacramento 5 Ese, CA (3 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.