Irmo weather by month
What a typical year looks like in Irmo, South Carolina: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at Columbia Metropolitan Airport, 19 km from Irmo; records cover 1887–2026.
The year at a glance
- Precipitation a year
- 45.2 in1149 mm
- Snow a year
- 1.2 in3 cm
- Last spring freeze
- Mar 23
- First fall freeze
- Nov 5
- Heating degree days
- 2,474
- Cooling degree days
- 2,237
Freeze dates are medians (half of years earlier, half later). Degree days use a 65°F base; HVAC design temperatures here are 21°−6° (heating, 99%) and 100°38° (cooling, 1%).
Month by month
Irmo in January
Highs average 57°14° and lows 35°1°, with 3.5 in89 mm of precipitation and 0.6 in1.5 cm of snow in a typical January.
- Record high
- 84°29° (1974)
- Record low
- −1°−18° (1985)
- Heating degree days
- 600
- Cooling degree days
- 2
Irmo in February
Highs average 61°16° and lows 37°3°, with 3.4 in86 mm of precipitation and 0.4 in1 cm of snow in a typical February.
- Record high
- 86°30° (2021)
- Record low
- −2°−19° (1899)
- Heating degree days
- 451
- Cooling degree days
- 4
Irmo in March
Highs average 68°20° and lows 44°6°, with 3.6 in91 mm of precipitation and 0.1 in0.3 cm of snow in a typical March.
- Record high
- 93°34° (1907)
- Record low
- 4°−16° (1980)
- Heating degree days
- 302
- Cooling degree days
- 21
Irmo in April
Highs average 77°25° and lows 52°11°, with 2.8 in72 mm of precipitation in a typical April.
- Record high
- 96°36° (1896)
- Record low
- 26°−3° (1983)
- Heating degree days
- 109
- Cooling degree days
- 82
Irmo in May
Highs average 84°29° and lows 61°16°, with 3.5 in89 mm of precipitation in a typical May.
- Record high
- 101°38° (1898)
- Record low
- 34°1° (1963)
- Heating degree days
- 18
- Cooling degree days
- 239
Irmo in June
Highs average 90°32° and lows 69°20°, with 5 in126 mm of precipitation in a typical June.
- Record high
- 109°43° (2012)
- Record low
- 44°7° (1984)
- Heating degree days
- 1
- Cooling degree days
- 425
Irmo in July
Highs average 93°34° and lows 72°22°, with 5.4 in136 mm of precipitation in a typical July.
- Record high
- 107°42° (1952)
- Record low
- 54°12° (1892)
- Heating degree days
- 0
- Cooling degree days
- 538
Irmo in August
Highs average 91°33° and lows 71°22°, with 4.7 in118 mm of precipitation in a typical August.
- Record high
- 107°42° (1983)
- Record low
- 53°12° (1969)
- Heating degree days
- 0
- Cooling degree days
- 496
Irmo in September
Highs average 86°30° and lows 65°19°, with 3.9 in99 mm of precipitation in a typical September.
- Record high
- 106°41° (1925)
- Record low
- 40°4° (1967)
- Heating degree days
- 6
- Cooling degree days
- 321
Irmo in OctoberThis month
Highs average 77°25° and lows 53°12°, with 3.1 in80 mm of precipitation in a typical October.
- Record high
- 101°38° (1954)
- Record low
- 23°−5° (1952)
- Heating degree days
- 104
- Cooling degree days
- 92
Irmo in November
Highs average 66°19° and lows 42°5°, with 2.8 in70 mm of precipitation in a typical November.
- Record high
- 90°32° (1961)
- Record low
- 12°−11° (1970)
- Heating degree days
- 343
- Cooling degree days
- 13
Irmo in December
Highs average 59°15° and lows 37°3°, with 3.7 in94 mm of precipitation and 0.1 in0.3 cm of snow in a typical December.
- Record high
- 83°28° (1971)
- Record low
- 4°−16° (1958)
- Heating degree days
- 540
- Cooling degree days
- 4