Frost Dates for O'Fallon, IL

Based on data from Belleville Siu Rsch weather station, 6 miles away

Frost Dates

Last Spring Frost (50%) iA 50% chance that the last spring frost has already passed by this date. Most gardeners use this as their primary planting guide. April 12
First Fall Frost (50%) iA 50% chance that the first fall frost has occurred by this date. Plan to harvest or protect tender plants before this date. October 20
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

30% Probability iOnly a 30% chance of frost remaining by this date. Use these dates for a safer planting window, especially for tender plants sensitive to cold.

Last Spring Frost April 19
First Fall Frost October 14

Hard Freeze (28°F)

Last Spring Hard Freeze March 31
First Fall Hard Freeze October 30
38.59°N, -89.91°W © OpenStreetMap

Growing Season

191 Days April 12 to October 20

USDA Hardiness Zone iHardiness zones indicate which perennial plants can survive winter in your area. For annual vegetables, frost dates and growing season length matter more than hardiness zone.

Zone 6b

Avg. annual minimum: −5 to 0°F (−21 to −18°C)

Learn more

Köppen Climate iThe Köppen climate classification system categorizes climates based on temperature and precipitation patterns.

Cfa Humid Subtropical

Hot, humid summers and mild winters with rain year-round. Long growing seasons support a wide variety of vegetables, fruits, and ornamentals. The most common climate in the eastern US.

Köppen climate map

Temperature

20° 40° 60° 80° 100°
34°
High: 43°F
Avg: 34°F
Low: 24°F
Jan
38°
High: 49°F
Avg: 38°F
Low: 28°F
Feb
48°
High: 59°F
Avg: 48°F
Low: 36°F
Mar
58°
High: 71°F
Avg: 58°F
Low: 46°F
Apr
68°
High: 79°F
Avg: 68°F
Low: 56°F
May
76°
High: 87°F
Avg: 76°F
Low: 65°F
Jun
79°
High: 90°F
Avg: 79°F
Low: 68°F
Jul
77°
High: 89°F
Avg: 77°F
Low: 65°F
Aug
70°
High: 83°F
Avg: 70°F
Low: 57°F
Sep
60°
High: 73°F
Avg: 60°F
Low: 47°F
Oct
48°
High: 58°F
Avg: 48°F
Low: 37°F
Nov
37°
High: 46°F
Avg: 37°F
Low: 28°F
Dec
32°F
28°F
Avg High Avg Temp Avg Low Light Frost (32°F) Hard Frost (28°F)

Precipitation

0" 3" 6" 9" 9.6"
4.8"
4.85"
Jan
4.1"
4.07"
Feb
6.8"
6.79"
Mar
8.3"
8.30"
Apr
7.9"
7.88"
May
8.3"
8.35"
Jun
9.4"
9.39"
Jul
9.6"
9.61"
Aug
6.9"
6.90"
Sep
6.3"
6.27"
Oct
7.0"
7.00"
Nov
5.8"
5.85"
Dec

Sunrise / Sunset

4a7a10a1p4p7p10pNoonJanFebMarAprMayJunJulAugSepOctNovDec9.5h10.5h11.5h13h14h14.5h14.5h13.5h12h11h10h9.5h
Jan: 7:12 AM – 4:48 PM · 9h 36m
Feb: 6:43 AM – 5:17 PM · 10h 33m
Mar: 6:09 AM – 5:51 PM · 11h 42m
Apr: 5:30 AM – 6:30 PM · 13h 01m
May: 4:57 AM – 7:03 PM · 14h 06m
Jun: 4:40 AM – 7:20 PM · 14h 41m
Jul: 4:47 AM – 7:13 PM · 14h 26m
Aug: 5:15 AM – 6:45 PM · 13h 30m
Sep: 5:53 AM – 6:07 PM · 12h 14m
Oct: 6:31 AM – 5:29 PM · 10h 58m
Nov: 7:04 AM – 4:56 PM · 9h 52m
Dec: 7:20 AM – 4:40 PM · 9h 19m
Daylight Longest: 14h 42m · Shortest: 9h 18m

Nearby Stations

Cahokia St Louis AP, IL April 8 - October 26 Cahokia, ILApril 6 - October 27 St Louis Sci Ctr, MO April 1 - November 4 Carlyle Rsvr, IL April 6 - October 29 Sparta 1 W, IL April 12 - October 22 Alton - Melvin Price L&D, IL April 4 - November 5

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