Frost dates for 61812Armstrong, IL
The average last spring frost in Armstrong is April 21 and the average first fall frost is October 18, giving a typical growing season of about 179 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 21
- Average first fall frost
- Oct 18
- Growing season
- 179 days
Safer after May 6 (1-in-10 risk)
Possible by Oct 5 (1-in-10 risk)
Last frost typically in 173 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 18 · Apr 30 · May 17 | Sep 26 · Oct 8 · Oct 20 | 159 days | 100% |
| Frost / freeze (32°F) | Apr 7 · Apr 21 · May 6 | Oct 5 · Oct 18 · Oct 31 | 179 days | 100% |
| Hard freeze (28°F) | Mar 30 · Apr 10 · Apr 26 | Oct 16 · Oct 29 · Nov 12 | 199 days | 100% |
Planting calendar for Armstrong
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 21 – May 27 |
| Tomatoes | Transplant outdoors | May 7 – Jun 28 |
| Peppers | Start seeds indoors | Mar 21 – Apr 21 |
| Peppers | Transplant outdoors | May 21 – Jun 21 |
| Eggplant | Start seeds indoors | Apr 7 – May 6 |
| Eggplant | Transplant outdoors | May 21 – Jun 21 |
| Cucumbers | Sow outdoors | May 21 – Jul 8 |
| Summer squash | Sow outdoors | May 7 – Jun 21 |
| Winter squash & pumpkins | Sow outdoors | May 21 – Jun 21 |
| Snap beans | Sow outdoors | May 7 – Jul 31 |
| Sweet corn | Sow outdoors | May 7 – Jun 28 |
| Watermelon & cantaloupe | Sow outdoors | May 21 – Jun 21 |
| Okra | Sow outdoors | May 14 – Jun 6 |
| Peas | Sow outdoors (spring) | Mar 21 – May 6 |
| Potatoes | Plant outdoors (spring) | Mar 21 – May 21 |
| Onions | Start seeds indoors (spring) | Feb 7 – Mar 6 |
| Onions | Transplant outdoors (spring) | Apr 7 – May 6 |
| Broccoli | Start seeds indoors (spring) | Mar 3 – Apr 6 |
| Broccoli | Transplant outdoors (spring) | Apr 7 – May 6 |
| Broccoli | Start seeds indoors (fall) | Jun 18 – Jun 28 |
| Broccoli | Transplant outdoors (fall) | Jul 18 – Jul 29 |
| Cabbage | Start seeds indoors (spring) | Feb 21 – Mar 21 |
| Cabbage | Transplant outdoors (spring) | Mar 21 – Apr 21 |
| Cabbage | Start seeds indoors (fall) | Jun 8 – Jul 8 |
| Cabbage | Transplant outdoors (fall) | Jul 8 – Aug 8 |
| Leaf lettuce | Sow outdoors (spring) | Mar 21 – Jun 6 |
| Leaf lettuce | Sow outdoors (fall) | Jul 8 – Aug 24 |
| Spinach | Sow outdoors (spring) | Mar 14 – Apr 27 |
| Spinach | Sow outdoors (fall) | Jul 25 – Aug 29 |
| Radishes | Sow outdoors (spring) | Mar 21 – May 11 |
| Radishes | Sow outdoors (fall) | Jul 8 – Sep 8 |
| Kale | Sow outdoors (spring) | Apr 7 – Apr 27 |
| Kale | Sow outdoors (fall) | Jul 1 – Aug 8 |
| Carrots | Sow outdoors (spring) | Apr 21 – Jun 6 |
| Carrots | Sow outdoors (fall) | Jun 8 – Jul 24 |
| Garlic | Plant outdoors (fall) | Oct 8 – Nov 8 |
Where these dates come from
ZIP code 61812 is matched to the NOAA station Rantoul, IL, 24.9 km away, at 740 ft elevation (5 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Rantoul, IL (used) | 740 ft | Apr 21 | Oct 18 |
| Ogden, IL | 675 ft | Apr 20 | Oct 21 |
| Danville, IL | 555 ft | Apr 21 | Oct 20 |
| Sidell 4N, IL | 672 ft | Apr 19 | Oct 19 |
Frost dates near Armstrong
- Royal, IL 61871 · last Apr 21, first Oct 18
- Collison, IL 61831 · last Apr 21, first Oct 20
- Ogden, IL 61859 · last Apr 20, first Oct 21
- Fithian, IL 61844 · last Apr 19, first Oct 19
- Penfield, IL 61862 · last Apr 21, first Oct 18
- Potomac, IL 61865 · last Apr 22, first Oct 19
- Muncie, IL 61857 · last Apr 19, first Oct 19
- Oakwood, IL 61858 · last Apr 21, first Oct 20
Frequently asked questions
- When is the last frost in Armstrong, IL?
- For ZIP code 61812, the average last spring frost (32°F) is April 21, based on NOAA 1991-2020 climate normals for the Rantoul, IL weather station. There is a 1-in-10 chance of a frost after May 6.
- When is the first frost in Armstrong, IL?
- The average first fall frost (32°F) is October 18. There is a 1-in-10 chance of frost by October 5, so tender plants are at risk from that point on.
- How long is the growing season in 61812?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 179 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.