Frost Dates for St. Louis, MO
In St. Louis, MO, the average last spring frost is around Apr 1 and the average first fall frost around Nov 4, for a growing season of about 218 days. For frost-tender plants, wait until Apr 18, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the St Louis Sci Ctr, MO weather station, 1 mile away, elevation 515 ft. Frost can come earlier in low spots and valleys and later near cities and large lakes.
Frost probability by date
Chance of a 32°F frost after the spring date, or before the fall date.
| Chance | Last spring frost | First fall frost |
|---|---|---|
| 10% | Apr 18 | Oct 24 |
| 20% | Apr 11 | Oct 28 |
| 30% | Apr 7 | Oct 31 |
| 40% | Apr 4 | Nov 2 |
| 50% | Apr 1 | Nov 4 |
| 60% | Mar 29 | Nov 7 |
| 70% | Mar 26 | Nov 10 |
| 80% | Mar 21 | Nov 14 |
| 90% | Mar 14 | Nov 21 |
Light frost vs. hard freeze
Average (50%) dates for each temperature. Tender plants are damaged at 36°F; most hardy crops survive until 28°F.
| Temperature | Last in spring | First in fall |
|---|---|---|
| Light frost (36°F) | Apr 12 | Oct 26 |
| Frost / freeze (32°F) | Apr 1 | Nov 4 |
| Hard freeze (28°F) | Mar 22 | Nov 15 |
Planting calendar for St. Louis
Transplant Apr 8 – Apr 22
Transplant Apr 15 – Apr 29
Transplant Apr 15 – Apr 29
Transplant Apr 8 – Apr 22
Sow or transplant Apr 8 – Apr 22
Sow or transplant Apr 8 – Apr 22
Sow or transplant Apr 15 – Apr 29
Sow or transplant Mar 4 – Mar 18
Fall sowing Sep 9 – Oct 7
Fall sowing Sep 9 – Sep 30
Fall sowing Aug 26 – Sep 9
Sow or transplant Mar 4 – Mar 18
Fall sowing Aug 26 – Sep 23
Transplant Mar 18 – Apr 1
Fall sowing Aug 12 – Aug 26
Transplant Mar 11 – Mar 25
Fall sowing Aug 12 – Aug 26
Fall sowing Aug 12 – Aug 26
Fall sowing Sep 23 – Oct 14
Fall sowing Aug 26 – Sep 9
Plant Mar 4 – Mar 18
Based on the average last frost (Apr 1) and first frost (Nov 4). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.