Rockbridge, IL climate
Rockbridge has chilly winters and warm summers. A typical July afternoon reaches 87°, a January night drops to 21°, and about 18 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Rockbridge feels like
Winter
Spring
Summer
Fall
Rockbridge 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 | 37° | 21° | 2.3" | 5.8" | 8 | 8 | 22° – 40° |
| February | 43° | 25° | 2.1" | 4.5" | 7 | 6 | 22° – 43° |
| March | 54° | 33° | 3.0" | 2.5" | 10 | 2 | 36° – 57° |
| April | 66° | 43° | 4.4" | 0.3" | 11 | 0 | 47° – 61° |
| May | 75° | 54° | 4.9" | 0 | 12 | 0 | 60° – 73° |
| June | 84° | 63° | 4.4" | 0 | 9 | 0 | 69° – 77° |
| July | 87° | 67° | 3.8" | 0 | 8 | 0 | 72° – 83° |
| August | 86° | 64° | 3.5" | 0 | 7 | 0 | 69° – 81° |
| September | 80° | 56° | 3.2" | 0 | 7 | 0 | 63° – 74° |
| October | 68° | 45° | 3.2" | 0 | 8 | 0 | 51° – 62° |
| November | 54° | 34° | 3.2" | 0.8" | 8 | 1 | 36° – 51° |
| December | 42° | 26° | 2.3" | 3.7" | 8 | 4 | 20° – 42° |
| Year | 65° | 44° | 40.2" | 17.6" | 103 | 20 |
“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 Rockbridge
Rockbridge gets 40 inches of rain and melted snow a year. May is the wettest month and February the driest. Rain or snow falls on about 103 days a year. Snow covers the ground about 20 days of the year.
About 187 frost-free days a year
In half of years the last 32° night comes by April 14 and the first one by October 19. That leaves about 187 frost-free days for gardens, longer than 60% of U.S. towns.
Heating and cooling a home in Rockbridge
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Rockbridge, 82% of that work is heating and 18% is cooling, so the furnace matters far more than the air conditioner.
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.
Rockbridge and its neighbors
Rockbridge borders 7 towns with climate data. January nights across them vary by 0.8°. Rubicon has the coldest January nights (20°) and Kane the hottest July afternoons (87°). Rockbridge’s January low is 21° and its July high 87°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Rockbridge 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 Rockbridge averaged 0.7° warmer than the 1900s. The biggest change is in December (+1.9°). The shift is smaller than in 90% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Rockbridge’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. December swings the most: between 1991 and 2020 its average temperature ranged from 20° to 42°. June is the most reliable, staying within 8°.
Common questions about Rockbridge’s climate
What is the coldest month in Rockbridge?
January, with a typical high of 37° and a low of 21°.
What is the hottest month in Rockbridge?
July, with a typical high of 87° and a low of 67°. About 29 days a year reach 90°.
How much snow does Rockbridge get?
About 18 inches in a normal winter, most of it in January.
When is the first frost in Rockbridge?
In half of years the first 32° night comes by October 19, and the last spring frost by April 14.
What is the rainiest month in Rockbridge?
May, with 4.9 inches of rain and melted snow. The year totals 40 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Rockbridge itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Greenfield, IL (4 mi, snow) and Jerseyville 2 Sw, IL (15 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.