Your nature year
O'Fallon, Missourithrough the year
Also for Wentzville, MO: the same nearby places.
When do frost, green-up and fall color come to O'Fallon?
Two Rivers Refuge, 14 miles from O'Fallon, is the nearest winter wildlife spot on this site, usually begin to arrive in October (local timing). Mingo Refuge (129 mi) is the pick for spring migration, April and May are the best months (local timing).
At NOAA's Weldon Spring NWS station, 6.3 miles away, the average first fall frost is Oct 26 and the last spring frost Apr 10, which leaves O'Fallon some 199 growing days. About 4 weeks pass between first leaf and first bloom here. The USA-NPN spring index puts first leaf here around Mar 16 and first bloom around Apr 15. Within 150 miles we follow 6 places, out to Swan Lake Refuge 146 miles to the northwest.
Updated Sep 27. Sources: US Census Bureau, 2024 Gazetteer (places) ↗ (opens in a new tab), US Census Bureau, city and town population estimates, 2024 ↗ (opens in a new tab), NOAA NCEI U.S. Climate Normals 1991–2020 (annual/seasonal) ↗ (opens in a new tab)
Near O'Fallon right now
- First fall frost usually around Oct 26 · last spring frost around Apr 10NOAA 1991–2020 normals, Weldon Spring NWS (6.3 mi, 50% dates)~4 weeks
- Winter wildlife · Two Rivers Refuge · 14 miLocal timing: usually begin to arrive in October~1 day
Your guide around O'Fallon
Nearby, season by season
Spring migration
- Mingo Refuge · 129 miLocal timing: April and May are the best months~6 months
- Swan Lake Refuge · 146 miLocal timing: April and May~6 months
Winter wildlife
- Two Rivers Refuge · 14 miLocal timing: usually begin to arrive in October~1 day
- Meredosia Refuge · 74 miUsually: migration typically peaks in November~5 weeks
- Emiquon Refuge · 112 miUsually: migration typically peaks in November~5 weeks
O'Fallon's nature year
- Mar: Spring green-upMar
- Spring migration · Mingo RefugeApr–May
- Apr: Last spring frostApr
- Oct: First fall frostOct
- Oct: Winter wildlife · Two Rivers RefugeOct
O'Fallon's year at a glance
- Frost possible
- Frost-free, ~Apr 10 to ~Oct 26
- First leaf ~Mar 16
- First bloom ~Apr 15
- Today
Frost and green-up
Last spring frost
Apr 10
Average (50% date)
First fall frost
Oct 26
About 199 days without frost between
Spring green-up
Mar 16
First bloom around Apr 15
Frost: NOAA 1991–2020 climate normals at Weldon Spring NWS (6.3 mi from O'Fallon), the day a 32 °F night is as likely as not. Green-up: the USA-NPN Spring Index, 1991–2020 average at the town.
Snow in O'Fallon
Snow usually becomes possible around Jan 13 (our calculation from NOAA's daily snow chances: the first day the chance of 0.1" or more of snow reaches 10%). NOAA's normals at Weldon Spring NWS (6.3 mi away): 14 inches of snow in an average year, about 4.8 days with 1 inch or more.
NOAA's chance of at least 0.1 inch of snow on each date (one value per week, September to May), averaged over 1991–2020. A typical year, not a forecast.
Questions people ask
When is the first frost in O'Fallon?
On average around Oct 26, and the last spring frost around Apr 10: about 199 days without frost between. These are NOAA's 1991–2020 normals at Weldon Spring NWS, 6.3 miles away (the day a 32 °F night is as likely as not).
When does spring green-up reach O'Fallon?
The USA-NPN Spring Index puts first leaf around Mar 16 and first bloom around Apr 15, on average for 1991–2020 at the town.
Where can I see spring migration near O'Fallon?
Mingo Refuge, 129 miles (local timing: April and May are the best months); Swan Lake Refuge, 146 miles (local timing: April and May). Distances are straight-line.
Where can I see winter wildlife near O'Fallon?
Two Rivers Refuge, 14 miles (local timing: usually begin to arrive in October); Meredosia Refuge, 74 miles (usually: migration typically peaks in November); Emiquon Refuge, 112 miles (usually: migration typically peaks in November). Distances are straight-line.
When does it start snowing in O'Fallon?
Snow usually becomes possible around Jan 13: our calculation from NOAA's daily snow chances: the first day the chance of 0.1" or more of snow reaches 10%, at Weldon Spring NWS. An average year brings 14 inches (NOAA 1991–2020). A typical year, not a forecast.Sources: NOAA NCEI U.S. Climate Normals 1991–2020 (annual/seasonal snowfall) ↗ (opens in a new tab), NOAA NCEI U.S. Climate Normals 1991–2020 (daily snowfall probabilities) ↗ (opens in a new tab)
How we know
US Census Bureau, 2024 Gazetteer (places) (opens in a new tab) (Sep 27) · US Census Bureau, city and town population estimates, 2024 (opens in a new tab) (Sep 27) · NOAA NCEI U.S. Climate Normals 1991–2020 (annual/seasonal) (opens in a new tab) (Sep 27) · USA National Phenology Network, Spring Index 1991–2020 averages (opens in a new tab) (Sep 27)