Olney, IL climate
Olney has chilly winters and warm summers. A typical July afternoon reaches 87°, a January night drops to 22°, and about 11 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Olney feels like
Winter
Spring
Summer
Fall
Olney 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 | 38° | 22° | 3.3" | 3.6" | 11 | 5 | 23° – 41° |
| February | 44° | 26° | 2.5" | 2.6" | 9 | 3 | 23° – 43° |
| March | 54° | 35° | 3.8" | 1.1" | 12 | 1 | 37° – 60° |
| April | 66° | 44° | 4.9" | 0 | 11 | 0 | 48° – 61° |
| May | 76° | 55° | 5.1" | 0 | 13 | 0 | 60° – 73° |
| June | 84° | 63° | 4.9" | 0 | 11 | 0 | 69° – 78° |
| July | 87° | 67° | 4.5" | 0 | 9 | 0 | 71° – 84° |
| August | 86° | 65° | 3.3" | 0 | 8 | 0 | 71° – 81° |
| September | 80° | 57° | 3.4" | 0 | 8 | 0 | 65° – 74° |
| October | 69° | 45° | 3.6" | 0 | 9 | 0 | 52° – 62° |
| November | 54° | 35° | 3.9" | 0.5" | 10 | 0 | 37° – 51° |
| December | 43° | 27° | 3.1" | 2.7" | 11 | 4 | 21° – 44° |
| Year | 65° | 45° | 46.3" | 10.5" | 120 | 14 |
“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 Olney
Olney gets 46 inches of rain and melted snow a year. May is the wettest month and February the driest. Rain or snow falls on about 120 days a year. Snow covers the ground about 14 days of the year.
About 189 frost-free days a year
In half of years the last 32° night comes by April 15 and the first one by October 23. That leaves about 189 frost-free days for gardens, longer than 63% of U.S. towns.
Heating and cooling a home in Olney
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Olney, 81% of that work is heating and 19% 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.
How Olney 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 Olney averaged 0.8° warmer than the 1900s. The biggest change is in February (+1.6°). The shift is smaller than in 82% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Olney’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 37° to 60°. June is the most reliable, staying within 9°.
Common questions about Olney’s climate
What is the coldest month in Olney?
January, with a typical high of 38° and a low of 22°.
What is the hottest month in Olney?
July, with a typical high of 87° and a low of 67°. About 32 days a year reach 90°.
How much snow does Olney get?
About 11 inches in a normal winter, most of it in January.
When is the first frost in Olney?
In half of years the first 32° night comes by October 23, and the last spring frost by April 15.
What is the rainiest month in Olney?
May, with 5.1 inches of rain and melted snow. The year totals 46 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Olney itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Olney 2s, IL (2 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.