Frost dates for 63166Saint Louis, MO
The average last spring frost in Saint Louis is April 1 and the average first fall frost is November 4, giving a typical growing season of about 218 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 1
- Average first fall frost
- Nov 4
- Growing season
- 218 days
Safer after Apr 18 (1-in-10 risk)
Possible by Oct 24 (1-in-10 risk)
First frost typically in 18 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | Mar 27 · Apr 12 · Apr 27 | Oct 15 · Oct 26 · Nov 7 | 197 days | 100% |
| Frost / freeze (32°F) | Mar 14 · Apr 1 · Apr 18 | Oct 24 · Nov 4 · Nov 21 | 218 days | 100% |
| Hard freeze (28°F) | Mar 5 · Mar 22 · Apr 7 | Nov 2 · Nov 15 · Dec 4 | 239 days | 100% |
Planting calendar for Saint Louis
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | Mar 1 – May 7 |
| Tomatoes | Transplant outdoors | Apr 17 – Jul 15 |
| Peppers | Start seeds indoors | Mar 1 – Apr 1 |
| Peppers | Transplant outdoors | May 1 – Jun 1 |
| Eggplant | Start seeds indoors | Mar 18 – Apr 16 |
| Eggplant | Transplant outdoors | May 1 – Jun 1 |
| Cucumbers | Sow outdoors | May 1 – Jul 25 |
| Summer squash | Sow outdoors | Apr 17 – Jun 1 |
| Winter squash & pumpkins | Sow outdoors | May 1 – Jun 1 |
| Snap beans | Sow outdoors | Apr 17 – Aug 17 |
| Sweet corn | Sow outdoors | Apr 17 – Jul 15 |
| Watermelon & cantaloupe | Sow outdoors | May 1 – Jun 1 |
| Okra | Sow outdoors | Apr 24 – May 17 |
| Peas | Sow outdoors (spring) | Mar 1 – Apr 16 |
| Potatoes | Plant outdoors (spring) | Mar 1 – May 1 |
| Onions | Start seeds indoors (spring) | Jan 18 – Feb 14 |
| Onions | Transplant outdoors (spring) | Mar 18 – Apr 16 |
| Broccoli | Start seeds indoors (spring) | Feb 11 – Mar 17 |
| Broccoli | Transplant outdoors (spring) | Mar 18 – Apr 16 |
| Broccoli | Start seeds indoors (fall) | Jul 5 – Jul 15 |
| Broccoli | Transplant outdoors (fall) | Aug 4 – Aug 15 |
| Cabbage | Start seeds indoors (spring) | Feb 1 – Mar 1 |
| Cabbage | Transplant outdoors (spring) | Mar 1 – Apr 1 |
| Cabbage | Start seeds indoors (fall) | Jun 25 – Jul 25 |
| Cabbage | Transplant outdoors (fall) | Jul 25 – Aug 25 |
| Leaf lettuce | Sow outdoors (spring) | Mar 1 – May 17 |
| Leaf lettuce | Sow outdoors (fall) | Jul 25 – Sep 10 |
| Spinach | Sow outdoors (spring) | Feb 22 – Apr 7 |
| Spinach | Sow outdoors (fall) | Aug 11 – Sep 15 |
| Radishes | Sow outdoors (spring) | Mar 1 – Apr 21 |
| Radishes | Sow outdoors (fall) | Jul 25 – Sep 25 |
| Kale | Sow outdoors (spring) | Mar 18 – Apr 7 |
| Kale | Sow outdoors (fall) | Jul 18 – Aug 25 |
| Carrots | Sow outdoors (spring) | Apr 1 – May 17 |
| Carrots | Sow outdoors (fall) | Jun 25 – Aug 10 |
| Garlic | Plant outdoors (fall) | Oct 25 – Nov 25 |
Where these dates come from
ZIP code 63166 is matched to the NOAA station St Louis Sci Ctr, MO, 3.4 km away, at 515 ft elevation (10 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| St Louis Sci Ctr, MO (used) | 515 ft | Apr 1 | Nov 4 |
| Cahokia, IL | 400 ft | Apr 6 | Oct 27 |
| Cahokia St Louis Ap, IL | 413 ft | Apr 8 | Oct 26 |
| St Louis Lambert Intl Ap, MO | 531 ft | Apr 2 | Nov 4 |
Frost dates near Saint Louis
- Saint Louis, MO 63156 · last Apr 1, first Nov 4
- Venice, IL 62090 · last Apr 8, first Oct 26
- National Stock Yards, IL 62071 · last Apr 8, first Oct 26
- Madison, IL 62060 · last Apr 8, first Oct 26
- East Saint Louis, IL 62202 · last Apr 8, first Oct 26
- East Carondelet, IL 62240 · last Apr 6, first Oct 27
- Granite City, IL 62040 · last Apr 4, first Nov 5
- Saint Ann, MO 63074 · last Apr 2, first Nov 4
Frequently asked questions
- When is the last frost in Saint Louis, MO?
- For ZIP code 63166, the average last spring frost (32°F) is April 1, based on NOAA 1991-2020 climate normals for the St Louis Sci Ctr, MO weather station. There is a 1-in-10 chance of a frost after April 18.
- When is the first frost in Saint Louis, MO?
- The average first fall frost (32°F) is November 4. There is a 1-in-10 chance of frost by October 24, so tender plants are at risk from that point on.
- How long is the growing season in 63166?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 218 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.