Frost dates · USDA zone 6b
Frost dates for St. Charles, MO
St. Charles, MO sees its last 32 °F night of spring around April 8 and its first of fall around October 29 — a 203-day freeze-free season in a typical year.
Pick a sauce; the Plan Builder runs this station's dates and hands back the calendar, plant count and gear list.
Freeze odds, by date
| Odds | Last spring freeze after | First fall freeze before |
|---|---|---|
| 9 years in 10 | Mar 23 | Nov 12 |
| Median — 1 year in 2 | Apr 8 | Oct 29 |
| 1 year in 10 | Apr 24 | Oct 16 |
The top row is the risky edge: in 9 years of 10 a spring freeze still comes after it, so tender transplants set out then need cover. The bottom row is the cautious date — only 1 year in 10 freezes after it — and the one to plan uncovered tender transplants against. Freeze-free season: 203 days median, at least 183 in 9 years of 10, at least 225 days in 1 year of 10. NOAA ranks season length year by year, so it is not the gap between two rows above. A hard freeze (28 °F) has a median last date of Mar 30 and first of Nov 10.
St. Charles planting calendar, 2027
Every row runs from the median last frost (Apr 8) and median first frost (Oct 29) above, using each cultivar's days to maturity. Same engine as the Plan Builder.
| Crop | Start indoors | Transplant / plant | First harvest | Days |
|---|---|---|---|---|
| Hardneck GarlicSiberian (porcelain hardneck) | — | Oct 15prior fall | Jun 12 | 240 from sow |
| Spanish OnionYellow Sweet Spanish (long-day) | Jan 14 | Mar 11 | Jun 29 | 110 from transplant |
| Mustard greensGarnet Giant (Brassica juncea) | Direct sow | Apr 8 | May 8 | 30 from sow |
| CilantroSlow Bolt (Coriandrum sativum) | Mar 25 | Mar 25 | May 9 | 45 from sow |
| Genovese BasilGenovese | Mar 11 | Apr 22 | Jun 21 | 60 from transplant |
| CayenneLong Slim Cayenne (Capsicum annuum) | Feb 11 | Apr 15 | Jun 29 | 75 from transplant |
| HabaneroOrange Habanero (Capsicum chinense) | Jan 28 | Apr 22 | Jul 26 | 95 from transplant |
| JalapeñoEarly Jalapeño (Capsicum annuum) | Feb 11 | Apr 15 | Jun 29 | 75 from transplant |
| Marconi Red PepperMarconi Red (Capsicum annuum) | Feb 11 | Apr 15 | Jul 4 | 80 from transplant |
| SerranoSerrano Tampiqueño (Capsicum annuum) | Feb 11 | Apr 15 | Jul 4 | 80 from transplant |
| Nantes CarrotScarlet Nantes | Mar 25 | Mar 25 | Jun 3 | 70 from sow |
| TomatilloToma Verde | Feb 25 | Apr 15 | Jun 24 | 70 from transplant |
| Roma TomatoRoma VF (determinate paste) | Feb 25 | Apr 15 | Jun 29 | 75 from transplant |
| San Marzano TomatoSan Marzano (indeterminate paste) | Feb 25 | Apr 15 | Jul 4 | 80 from transplant |
Tight means first harvest lands within two weeks of the median first fall frost: start that crop indoors on time or cover it in fall.
What sauce can St. Charles grow?
Each sauce, scheduled for a St. Charles container garden: when the first seeds go in and when enough fruit has ripened for one batch.
St. Charles frost questions
When is the last frost in St. Charles, MO?
The median last 32 °F freeze at ST CHARLES ELM PT, MO is April 8: half of years see a later one. One year in ten, a freeze still comes after April 24; nine years in ten, it comes after March 23. Source: NOAA NCEI 1991–2020 U.S. Climate Normals.
When is the first frost in St. Charles, MO?
The median first 32 °F freeze of fall is October 29. One year in ten it arrives before October 16; nine years in ten, before November 12.
How long is the growing season in St. Charles, MO?
203 days between the last spring and first fall 32 °F freeze in a median year. Nine years in ten the season runs at least 183 days; one year in ten, at least 225 days.
What growing zone is St. Charles, MO?
USDA hardiness zone 6b, per the 2023 USDA Plant Hardiness Zone Map for ZIP 63045. A zone describes the coldest winter night, not when frost ends, so it is the wrong number for a planting calendar — the frost dates on this page are the right one.
When should I plant tomatoes in St. Charles, MO?
Start Roma VF (determinate paste) seeds indoors around Feb 25 and transplant around Apr 15, 1 week after the median last frost. To cut the freeze risk to one year in ten, wait for Apr 24. First ripe fruit lands around Jun 29.
When should I plant peppers in St. Charles, MO?
Sow jalapeño indoors on a heat mat around Feb 11; transplant no earlier than Apr 15, and wait past it until nights hold above 50 °F — that can run weeks later. First green pods around Jun 29.
Nearby in Missouri
- St. Peterslast frost Apr 9
- Chesterfieldlast frost Apr 4
- Florissantlast frost Apr 2
- O'Fallonlast frost Apr 10
- St. Louislast frost Apr 1
- Wentzvillelast frost Apr 10
All Missouri frost dates → · How frost-date math drives a sowing calendar →