Princeton, IL climate
Princeton has cold winters and warm summers. A typical July afternoon reaches 84°, a January night drops to 14°, and about 29 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Princeton feels like
Winter
Spring
Summer
Fall
Princeton 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 | 30° | 14° | 1.8" | 8.6" | 8 | 17 | 13° – 35° |
| February | 36° | 18° | 1.8" | 6.9" | 8 | 12 | 13° – 38° |
| March | 48° | 28° | 2.5" | 3.7" | 8 | 4 | 29° – 54° |
| April | 62° | 38° | 3.8" | 0.9" | 10 | 0 | 41° – 58° |
| May | 73° | 50° | 4.8" | 0 | 11 | 0 | 55° – 67° |
| June | 82° | 59° | 4.7" | 0 | 10 | 0 | 67° – 75° |
| July | 84° | 63° | 3.7" | 0 | 8 | 0 | 68° – 81° |
| August | 82° | 61° | 3.7" | 0 | 8 | 0 | 66° – 78° |
| September | 77° | 53° | 3.6" | 0 | 8 | 0 | 59° – 69° |
| October | 64° | 41° | 3.1" | 0.3" | 9 | 0 | 48° – 59° |
| November | 48° | 31° | 2.6" | 1.3" | 8 | 1 | 31° – 49° |
| December | 36° | 20° | 2.1" | 6.8" | 8 | 9 | 14° – 38° |
| Year | 60° | 40° | 38.2" | 28.5" | 103 | 43 |
“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 Princeton
Princeton gets 38 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 43 days of the year.
About 177 frost-free days a year
In half of years the last 32° night comes by April 22 and the first one by October 17. That leaves about 177 frost-free days for gardens, shorter than 51% of U.S. towns.
Heating and cooling a home in Princeton
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Princeton, 88% of that work is heating and 12% 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.
Princeton and its neighbors
Princeton borders 2 towns with climate data. January nights across them vary by 0.2°. Dover has the coldest January nights (14°) and Princeton the hottest July afternoons (84°). Princeton’s January low is 14° and its July high 84°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Princeton 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 Princeton averaged 1.0° warmer than the 1900s. The biggest change is in December (+2.5°). The shift is smaller than in 73% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Princeton’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. March swings the most: between 1991 and 2020 its average temperature ranged from 29° to 54°. June is the most reliable, staying within 8°.
Common questions about Princeton’s climate
What is the coldest month in Princeton?
January, with a typical high of 30° and a low of 14°.
What is the hottest month in Princeton?
July, with a typical high of 84° and a low of 63°. About 19 days a year reach 90°.
How much snow does Princeton get?
About 29 inches in a normal winter, most of it in January.
When is the first frost in Princeton?
In half of years the first 32° night comes by October 17, and the last spring frost by April 22.
What is the rainiest month in Princeton?
May, with 4.8 inches of rain and melted snow. The year totals 38 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Princeton itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Princeton, IL (1 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.