USDA Hardiness Zone 7a
Frost Dates for 63125 — Saint Louis, Missouri
NOAA 1991–2020 normals from Cahokia, IL (400 ft), 6 miles northeast.
Updated
In Saint Louis, the last spring frost (32°F) is around April 6 in half of years and has passed by April 20 in nine years out of ten. The first fall frost comes around October 27, as early as October 14 one year in ten, leaving a typical freeze-free season of 203 days (NOAA, Cahokia, IL).
- Last spring frost
- April 6
- First fall frost
- October 27
- Growing season
- 203 days
- Hardiness zone
- 7a
50% probability
50% probability
freeze-free, 50%
0 to 5°F (-17.8 to -15.0°C) coldest night
- First snow
- December 12
- Last snow
- March 14
- Winters with snow
- 100%
- Snow per year
- 13.8"
median, 1991–2020
median, 1991–2020
19 of 19 observed
NOAA normal
Frost risk by date in Saint Louis
Half of springs at Cahokia, IL see their last 32°F night by April 6; only one in ten is past it by March 22, and one in ten still has one after April 20. Planting tender crops after April 12 leaves a 30% risk of a frost on them, after April 16 20%, and after April 20 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 80% of the 158 Missouri stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 27 in half of years, as early as October 14 one year in ten, and holds off past November 7 one year in ten. A hard freeze of 28°F follows 9 days later, around November 5; in spring the one-in-ten date for 28°F is April 10, 10 days before the 32°F one. The freeze-free season lasts 203 days in a typical year, longer than at 78% of the 158 Missouri stations; it reaches 223 days one year in ten and falls short of 184 one year in ten. On average 97 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 12 days longer, to about April 18, and return around October 18. Severe cold of 16°F or below comes every winter, usually between December 10 and February 28.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 4 | Apr 8 | Apr 12 | Apr 15 | Apr 18 | Apr 21 | Apr 24 | Apr 28 | May 3 |
| 32°F | Mar 22 | Mar 28 | Mar 31 | Apr 3 | Apr 6 | Apr 9 | Apr 12 | Apr 16 | Apr 20 |
| 28°F | Mar 11 | Mar 15 | Mar 20 | Mar 24 | Mar 27 | Mar 30 | Apr 2 | Apr 5 | Apr 10 |
| 24°F | Feb 28 | Mar 5 | Mar 9 | Mar 13 | Mar 15 | Mar 19 | Mar 22 | Mar 26 | Mar 31 |
| 20°F | Feb 16 | Feb 24 | Feb 28 | Mar 3 | Mar 6 | Mar 9 | Mar 12 | Mar 16 | Mar 21 |
| 16°F | Feb 1 | Feb 11 | Feb 18 | Feb 23 | Feb 28 | Mar 2 | Mar 6 | Mar 9 | Mar 14 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 5 | Oct 10 | Oct 13 | Oct 16 | Oct 18 | Oct 20 | Oct 22 | Oct 25 | Oct 28 |
| 32°F | Oct 14 | Oct 20 | Oct 22 | Oct 25 | Oct 27 | Oct 29 | Oct 31 | Nov 2 | Nov 7 |
| 28°F | Oct 25 | Oct 29 | Nov 1 | Nov 3 | Nov 5 | Nov 8 | Nov 12 | Nov 16 | Nov 23 |
| 24°F | Nov 3 | Nov 6 | Nov 10 | Nov 14 | Nov 18 | Nov 22 | Nov 26 | Dec 1 | Dec 6 |
| 20°F | Nov 9 | Nov 16 | Nov 21 | Nov 25 | Nov 29 | Dec 2 | Dec 6 | Dec 11 | Dec 18 |
| 16°F | Nov 20 | Nov 27 | Dec 1 | Dec 5 | Dec 10 | Dec 14 | Dec 18 | Dec 23 | Dec 29 |
Freeze probabilities 1991–2020 at Cahokia, IL, from NOAA NCEI U.S. Climate Normals. Where a temperature is reached in fewer than 99.5% of years, the dates describe only the years that reach it. Not a forecast.
Frost risk on any date in 63125 →Compare Saint Louis with another place →
Weather by month in Saint Louis
July is the warmest month at Cahokia, IL, averaging 89°F by day and 69°F at night; January is the coldest at 41°F and 22°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 70% of years.
Warmth for growing adds up to 4,249 growing degree days a year (base 50°F), more than at 75% of the 158 Missouri stations. 37% of them (1,583) have built up by the end of June, and July adds the most, 890. Precipitation totals 42.9 inches a year, most in July (5.0") and least in February (2.3"); May to September bring 48% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 41 | 22 | 2.7 | 100% | 25 | 5 |
| Feb | 46 | 26 | 2.3 | 100% | 20 | 14 |
| Mar | 56 | 35 | 3.6 | 99% | 13 | 81 |
| Apr | 68 | 45 | 4.6 | 70% | 3 | 240 |
| May | 76 | 56 | 4.8 | 0% | 0 | 499 |
| Jun | 85 | 65 | 4.3 | 0% | 0 | 745 |
| Jul | 89 | 69 | 5.0 | 0% | 0 | 890 |
| Aug | 87 | 67 | 3.1 | 0% | 0 | 837 |
| Sep | 80 | 59 | 3.4 | 1% | 0 | 584 |
| Oct | 70 | 46 | 3.0 | 72% | 2 | 273 |
| Nov | 56 | 35 | 3.3 | 100% | 11 | 70 |
| Dec | 45 | 27 | 2.8 | 100% | 23 | 13 |
Monthly normals 1991–2020 at Cahokia, IL (400 ft), NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.
Compared with the next station
The nearest other station, St Louis Sci Ctr, MO, 7 miles north of Saint Louis, has a last frost 5 days earlier (April 1), a first frost 8 days later (November 4), a season 15 days longer.
When it snows in Saint Louis, Missouri
The first measurable snow (0.1 inch or more) in Saint Louis usually arrives around December 12, and the last of the season around March 14. Those are the middle dates across the winters of 1991–2020 at Cahokia, IL, 5.9 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 23 days after the last snow.
Planting calendar for 63125
| When | What to do |
|---|---|
| January 26 – February 9 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 9 – February 23 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 9 – March 23 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 6 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 4 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 13 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 27 onward | Plant garlic, mulch beds, lift tender bulbsGarlic wants a cold spell; bare soil loses structure over winter. |
The weeks before and after the 50% dates are general rules of thumb, not NOAA figures; a seed packet gives the timing for each variety.
Where these figures come from
ZIP 63125 is 6 miles from Cahokia, IL, which stands at 400 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 6 other ZIP codes share the station; its figures are presented in full for 63129 (Saint Louis). The 2023 USDA Plant Hardiness Zone Map lists ZIP 63125 in zone 7a, the band where the coldest night of the year averaged 0 to 5°F (-17.8 to -15.0°C) over 1991–2020; a zone describes winter lows, not frost dates.
Hardiness zone and temperature range: USDA Plant Hardiness Zone Map 2023 (USDA-ARS, Oregon State University), ZIP-code listing, unchanged. °C converted from °F by this site.
Thirty-year averages, not a forecast: check the forecast before planting out. How stations are matched and which pages are offered to search engines: methodology.