Irmo, SC climate
Irmo has mild winters and hot summers. A typical July afternoon reaches 93°, a January night drops to 34°, and about 1 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Irmo feels like
Winter
Spring
Summer
Fall
Irmo 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 | 56° | 34° | 3.8" | 0.6" | 10 | 1 | 40° – 51° |
| February | 60° | 37° | 3.6" | 0.4" | 9 | 0 | 41° – 58° |
| March | 68° | 43° | 3.9" | 0.1" | 9 | 0 | 49° – 64° |
| April | 77° | 50° | 3.0" | 0 | 8 | 0 | 59° – 68° |
| May | 84° | 59° | 3.3" | 0 | 9 | 0 | 67° – 76° |
| June | 90° | 67° | 4.6" | 0 | 11 | 0 | 74° – 82° |
| July | 93° | 71° | 4.4" | 0 | 12 | 0 | 79° – 85° |
| August | 91° | 70° | 4.5" | 0 | 10 | 0 | 77° – 85° |
| September | 85° | 64° | 4.0" | 0 | 8 | 0 | 71° – 80° |
| October | 76° | 52° | 3.3" | 0 | 7 | 0 | 60° – 69° |
| November | 66° | 41° | 3.1" | 0 | 7 | 0 | 49° – 59° |
| December | 58° | 36° | 3.9" | 0.1" | 9 | 0 | 38° – 58° |
| Year | 75° | 52° | 45.4" | 1.2" | 109 | 1 |
“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 Irmo
Irmo gets 45 inches of rain and melted snow a year. June is the wettest month and April the driest. Rain or snow falls on about 109 days a year.
About 229 frost-free days a year
In half of years the last 32° night comes by March 25 and the first one by November 7. That leaves about 229 frost-free days for gardens, longer than 86% of U.S. towns.
Heating and cooling a home in Irmo
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Irmo, 53% of that work is heating and 47% 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.
Irmo and its neighbors
Irmo borders 3 towns with climate data. January nights across them vary by 0.9°. Lake Murray of Richland has the coldest January nights (34°) and Seven Oaks the hottest July afternoons (93°). Irmo’s January low is 34° and its July high 93°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Irmo 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 Irmo averaged 1.1° warmer than the 1900s. The biggest change is in February (+2.0°). The shift is smaller than in 60% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Irmo’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 38° to 58°. July is the most reliable, staying within 7°.
Common questions about Irmo’s climate
What is the coldest month in Irmo?
January, with a typical high of 56° and a low of 34°.
What is the hottest month in Irmo?
July, with a typical high of 93° and a low of 71°. About 81 days a year reach 90°.
How much snow does Irmo get?
About 1 inches in a normal winter, most of it in January.
When is the first frost in Irmo?
In half of years the first 32° night comes by November 7, and the last spring frost by March 25.
What is the rainiest month in Irmo?
June, with 4.6 inches of rain and melted snow. The year totals 45 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Irmo itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Columbia, SC (11 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.