Frost dates for 62443Mason, IL
The average last spring frost in Mason is April 13 and the average first fall frost is October 24, giving a typical growing season of about 191 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 13
- Average first fall frost
- Oct 24
- Growing season
- 191 days
Safer after Apr 29 (1-in-10 risk)
Possible by Oct 9 (1-in-10 risk)
Last frost typically in 165 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) | Apr 10 · Apr 24 · May 11 | Sep 29 · Oct 13 · Oct 25 | 170 days | 100% |
| Frost / freeze (32°F) | Apr 1 · Apr 13 · Apr 29 | Oct 9 · Oct 24 · Nov 5 | 191 days | 100% |
| Hard freeze (28°F) | Mar 17 · Apr 2 · Apr 17 | Oct 20 · Nov 1 · Nov 19 | 214 days | 100% |
Planting calendar for Mason
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 13 – May 19 |
| Tomatoes | Transplant outdoors | Apr 29 – Jul 4 |
| Peppers | Start seeds indoors | Mar 13 – Apr 13 |
| Peppers | Transplant outdoors | May 13 – Jun 13 |
| Eggplant | Start seeds indoors | Mar 30 – Apr 28 |
| Eggplant | Transplant outdoors | May 13 – Jun 13 |
| Cucumbers | Sow outdoors | May 13 – Jul 14 |
| Summer squash | Sow outdoors | Apr 29 – Jun 13 |
| Winter squash & pumpkins | Sow outdoors | May 13 – Jun 13 |
| Snap beans | Sow outdoors | Apr 29 – Aug 6 |
| Sweet corn | Sow outdoors | Apr 29 – Jul 4 |
| Watermelon & cantaloupe | Sow outdoors | May 13 – Jun 13 |
| Okra | Sow outdoors | May 6 – May 29 |
| Peas | Sow outdoors (spring) | Mar 13 – Apr 28 |
| Potatoes | Plant outdoors (spring) | Mar 13 – May 13 |
| Onions | Start seeds indoors (spring) | Jan 30 – Feb 26 |
| Onions | Transplant outdoors (spring) | Mar 30 – Apr 28 |
| Broccoli | Start seeds indoors (spring) | Feb 23 – Mar 29 |
| Broccoli | Transplant outdoors (spring) | Mar 30 – Apr 28 |
| Broccoli | Start seeds indoors (fall) | Jun 24 – Jul 4 |
| Broccoli | Transplant outdoors (fall) | Jul 24 – Aug 4 |
| Cabbage | Start seeds indoors (spring) | Feb 13 – Mar 13 |
| Cabbage | Transplant outdoors (spring) | Mar 13 – Apr 13 |
| Cabbage | Start seeds indoors (fall) | Jun 14 – Jul 14 |
| Cabbage | Transplant outdoors (fall) | Jul 14 – Aug 14 |
| Leaf lettuce | Sow outdoors (spring) | Mar 13 – May 29 |
| Leaf lettuce | Sow outdoors (fall) | Jul 14 – Aug 30 |
| Spinach | Sow outdoors (spring) | Mar 6 – Apr 19 |
| Spinach | Sow outdoors (fall) | Jul 31 – Sep 4 |
| Radishes | Sow outdoors (spring) | Mar 13 – May 3 |
| Radishes | Sow outdoors (fall) | Jul 14 – Sep 14 |
| Kale | Sow outdoors (spring) | Mar 30 – Apr 19 |
| Kale | Sow outdoors (fall) | Jul 7 – Aug 14 |
| Carrots | Sow outdoors (spring) | Apr 13 – May 29 |
| Carrots | Sow outdoors (fall) | Jun 14 – Jul 30 |
| Garlic | Plant outdoors (fall) | Oct 14 – Nov 14 |
Where these dates come from
ZIP code 62443 is matched to the NOAA station Effingham 3Sw, IL, 17.1 km away, at 625 ft elevation (18 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Effingham 3Sw, IL (used) | 625 ft | Apr 13 | Oct 24 |
| Flora 5 Nw, IL | 500 ft | Apr 10 | Oct 23 |
| Brownstown 4 Sw, IL | 530 ft | Apr 3 | Oct 24 |
| Flora, IL | 481 ft | Apr 9 | Oct 24 |
Frost dates near Mason
- Watson, IL 62473 · last Apr 13, first Oct 24
- Edgewood, IL 62426 · last Apr 10, first Oct 23
- Altamont, IL 62411 · last Apr 13, first Oct 24
- Farina, IL 62838 · last Apr 3, first Oct 24
- Effingham, IL 62401 · last Apr 13, first Oct 24
- Dieterich, IL 62424 · last Apr 13, first Oct 22
- Saint Elmo, IL 62458 · last Apr 3, first Oct 24
- Teutopolis, IL 62467 · last Apr 13, first Oct 24
Frequently asked questions
- When is the last frost in Mason, IL?
- For ZIP code 62443, the average last spring frost (32°F) is April 13, based on NOAA 1991-2020 climate normals for the Effingham 3Sw, IL weather station. There is a 1-in-10 chance of a frost after April 29.
- When is the first frost in Mason, IL?
- The average first fall frost (32°F) is October 24. There is a 1-in-10 chance of frost by October 9, so tender plants are at risk from that point on.
- How long is the growing season in 62443?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 191 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.