Frost dates for 62946Harrisburg, IL
The average last spring frost in Harrisburg is April 7 and the average first fall frost is October 26, giving a typical growing season of about 202 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 7
- Average first fall frost
- Oct 26
- Growing season
- 202 days
Safer after Apr 25 (1-in-10 risk)
Possible by Oct 10 (1-in-10 risk)
Last frost typically in 159 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 3 · Apr 19 · May 5 | Oct 1 · Oct 16 · Oct 28 | 180 days | 100% |
| Frost / freeze (32°F) | Mar 21 · Apr 7 · Apr 25 | Oct 10 · Oct 26 · Nov 8 | 202 days | 100% |
| Hard freeze (28°F) | Mar 7 · Mar 26 · Apr 12 | Oct 23 · Nov 6 · Nov 25 | 226 days | 100% |
Planting calendar for Harrisburg
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 7 – May 13 |
| Tomatoes | Transplant outdoors | Apr 23 – Jul 6 |
| Peppers | Start seeds indoors | Mar 7 – Apr 7 |
| Peppers | Transplant outdoors | May 7 – Jun 7 |
| Eggplant | Start seeds indoors | Mar 24 – Apr 22 |
| Eggplant | Transplant outdoors | May 7 – Jun 7 |
| Cucumbers | Sow outdoors | May 7 – Jul 16 |
| Summer squash | Sow outdoors | Apr 23 – Jun 7 |
| Winter squash & pumpkins | Sow outdoors | May 7 – Jun 7 |
| Snap beans | Sow outdoors | Apr 23 – Aug 8 |
| Sweet corn | Sow outdoors | Apr 23 – Jul 6 |
| Watermelon & cantaloupe | Sow outdoors | May 7 – Jun 7 |
| Okra | Sow outdoors | Apr 30 – May 23 |
| Peas | Sow outdoors (spring) | Mar 7 – Apr 22 |
| Potatoes | Plant outdoors (spring) | Mar 7 – May 7 |
| Onions | Start seeds indoors (spring) | Jan 24 – Feb 20 |
| Onions | Transplant outdoors (spring) | Mar 24 – Apr 22 |
| Broccoli | Start seeds indoors (spring) | Feb 17 – Mar 23 |
| Broccoli | Transplant outdoors (spring) | Mar 24 – Apr 22 |
| Broccoli | Start seeds indoors (fall) | Jun 26 – Jul 6 |
| Broccoli | Transplant outdoors (fall) | Jul 26 – Aug 6 |
| Cabbage | Start seeds indoors (spring) | Feb 7 – Mar 7 |
| Cabbage | Transplant outdoors (spring) | Mar 7 – Apr 7 |
| Cabbage | Start seeds indoors (fall) | Jun 16 – Jul 16 |
| Cabbage | Transplant outdoors (fall) | Jul 16 – Aug 16 |
| Leaf lettuce | Sow outdoors (spring) | Mar 7 – May 23 |
| Leaf lettuce | Sow outdoors (fall) | Jul 16 – Sep 1 |
| Spinach | Sow outdoors (spring) | Feb 28 – Apr 13 |
| Spinach | Sow outdoors (fall) | Aug 2 – Sep 6 |
| Radishes | Sow outdoors (spring) | Mar 7 – Apr 27 |
| Radishes | Sow outdoors (fall) | Jul 16 – Sep 16 |
| Kale | Sow outdoors (spring) | Mar 24 – Apr 13 |
| Kale | Sow outdoors (fall) | Jul 9 – Aug 16 |
| Carrots | Sow outdoors (spring) | Apr 7 – May 23 |
| Carrots | Sow outdoors (fall) | Jun 16 – Aug 1 |
| Garlic | Plant outdoors (fall) | Oct 16 – Nov 16 |
Where these dates come from
ZIP code 62946 is matched to the NOAA station Harrisburg, IL, 2.4 km away, at 365 ft elevation (32 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Harrisburg, IL (used) | 365 ft | Apr 7 | Oct 26 |
| Rosiclare 5Nw, IL | 400 ft | Apr 19 | Oct 20 |
| Dixon Springs Agric Ctr, IL | 527 ft | Apr 14 | Oct 21 |
| Mcleansboro, IL | 446 ft | Apr 11 | Oct 21 |
Frost dates near Harrisburg
- Muddy, IL 62965 · last Apr 7, first Oct 26
- Carrier Mills, IL 62917 · last Apr 7, first Oct 26
- Raleigh, IL 62977 · last Apr 7, first Oct 26
- Stonefort, IL 62987 · last Apr 7, first Oct 26
- Eldorado, IL 62930 · last Apr 7, first Oct 26
- Galatia, IL 62935 · last Apr 7, first Oct 26
- Equality, IL 62934 · last Apr 7, first Oct 26
- Herod, IL 62947 · last Apr 19, first Oct 20
Frequently asked questions
- When is the last frost in Harrisburg, IL?
- For ZIP code 62946, the average last spring frost (32°F) is April 7, based on NOAA 1991-2020 climate normals for the Harrisburg, IL weather station. There is a 1-in-10 chance of a frost after April 25.
- When is the first frost in Harrisburg, IL?
- The average first fall frost (32°F) is October 26. There is a 1-in-10 chance of frost by October 10, so tender plants are at risk from that point on.
- How long is the growing season in 62946?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 202 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.