St. Augustine weather by month
What a typical year looks like in St. Augustine, Illinois: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at Knoxville, 22 km from St. Augustine; records cover 1897–2026.
The year at a glance
- Precipitation a year
- 40.5 in1029 mm
- Snow a year
- 25 in65 cm
- Last spring freeze
- Apr 23
- First fall freeze
- Oct 21
- Heating degree days
- 6,190
- Cooling degree days
- 899
Freeze dates are medians (half of years earlier, half later). Degree days use a 65°F base; HVAC design temperatures here are −8°−22° (heating, 99%) and 92°33° (cooling, 1%).
Month by month
St. Augustine in January
Highs average 32°0° and lows 14°−10°, with 2.1 in53 mm of precipitation and 6 in16 cm of snow in a typical January.
- Record high
- 68°20° (1909)
- Record low
- −27°−33° (2019)
- Heating degree days
- 1303
- Cooling degree days
- 0
St. Augustine in February
Highs average 36°2° and lows 18°−8°, with 2.1 in54 mm of precipitation and 8 in20 cm of snow in a typical February.
- Record high
- 75°24° (2024)
- Record low
- −28°−33° (1905)
- Heating degree days
- 1061
- Cooling degree days
- 0
St. Augustine in March
Highs average 49°9° and lows 29°−2°, with 2.6 in67 mm of precipitation and 3 in9 cm of snow in a typical March.
- Record high
- 85°29° (2026)
- Record low
- −8°−22° (2014)
- Heating degree days
- 818
- Cooling degree days
- 1
St. Augustine in April
Highs average 62°16° and lows 39°4°, with 4 in100 mm of precipitation and 0.4 in1 cm of snow in a typical April.
- Record high
- 88°31° (1899)
- Record low
- 9°−13° (1899)
- Heating degree days
- 443
- Cooling degree days
- 6
St. Augustine in May
Highs average 72°22° and lows 51°10°, with 5.5 in141 mm of precipitation in a typical May.
- Record high
- 94°34° (2018)
- Record low
- 24°−4° (1903)
- Heating degree days
- 172
- Cooling degree days
- 61
St. Augustine in June
Highs average 81°27° and lows 61°16°, with 4.6 in117 mm of precipitation in a typical June.
- Record high
- 99°37° (1901)
- Record low
- 36°2° (1903)
- Heating degree days
- 17
- Cooling degree days
- 196
St. Augustine in July
Highs average 84°29° and lows 65°18°, with 4.2 in106 mm of precipitation in a typical July.
- Record high
- 108°42° (1901)
- Record low
- 42°6° (1899)
- Heating degree days
- 3
- Cooling degree days
- 287
St. Augustine in August
Highs average 82°28° and lows 63°17°, with 3.5 in89 mm of precipitation in a typical August.
- Record high
- 100°38° (1900)
- Record low
- 43°6° (1904)
- Heating degree days
- 6
- Cooling degree days
- 232
St. Augustine in September
Highs average 76°25° and lows 54°12°, with 4.2 in106 mm of precipitation in a typical September.
- Record high
- 100°38° (1899)
- Record low
- 19°−7° (1899)
- Heating degree days
- 92
- Cooling degree days
- 102
St. Augustine in OctoberThis month
Highs average 64°18° and lows 42°5°, with 3 in77 mm of precipitation and 0.2 in0.5 cm of snow in a typical October.
- Record high
- 92°33° (1897)
- Record low
- 18°−8° (1909)
- Heating degree days
- 392
- Cooling degree days
- 14
St. Augustine in November
Highs average 49°10° and lows 31°−1°, with 2.5 in64 mm of precipitation and 1.4 in3.6 cm of snow in a typical November.
- Record high
- 78°26° (2016)
- Record low
- −6°−21° (1898)
- Heating degree days
- 750
- Cooling degree days
- 0
St. Augustine in December
Highs average 36°2° and lows 21°−6°, with 2.2 in55 mm of precipitation and 6 in15 cm of snow in a typical December.
- Record high
- 71°22° (2021)
- Record low
- −16°−27° (1901)
- Heating degree days
- 1133
- Cooling degree days
- 0