Frost dates for 46242Indianapolis, IN
The average last spring frost in Indianapolis is April 20 and the average first fall frost is October 21, giving a typical growing season of about 183 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 20
- Average first fall frost
- Oct 21
- Growing season
- 183 days
Safer after May 5 (1-in-10 risk)
Possible by Oct 7 (1-in-10 risk)
First frost typically in 4 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 16 · Apr 30 · May 17 | Sep 27 · Oct 11 · Oct 24 | 161 days | 100% |
| Frost / freeze (32°F) | Apr 6 · Apr 20 · May 5 | Oct 7 · Oct 21 · Nov 3 | 183 days | 100% |
| Hard freeze (28°F) | Mar 25 · Apr 7 · Apr 23 | Oct 20 · Nov 1 · Nov 15 | 205 days | 100% |
Planting calendar for Indianapolis
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 20 – May 26 |
| Tomatoes | Transplant outdoors | May 6 – Jul 1 |
| Peppers | Start seeds indoors | Mar 20 – Apr 20 |
| Peppers | Transplant outdoors | May 20 – Jun 20 |
| Eggplant | Start seeds indoors | Apr 6 – May 5 |
| Eggplant | Transplant outdoors | May 20 – Jun 20 |
| Cucumbers | Sow outdoors | May 20 – Jul 11 |
| Summer squash | Sow outdoors | May 6 – Jun 20 |
| Winter squash & pumpkins | Sow outdoors | May 20 – Jun 20 |
| Snap beans | Sow outdoors | May 6 – Aug 3 |
| Sweet corn | Sow outdoors | May 6 – Jul 1 |
| Watermelon & cantaloupe | Sow outdoors | May 20 – Jun 20 |
| Okra | Sow outdoors | May 13 – Jun 5 |
| Peas | Sow outdoors (spring) | Mar 20 – May 5 |
| Potatoes | Plant outdoors (spring) | Mar 20 – May 20 |
| Onions | Start seeds indoors (spring) | Feb 6 – Mar 5 |
| Onions | Transplant outdoors (spring) | Apr 6 – May 5 |
| Broccoli | Start seeds indoors (spring) | Mar 2 – Apr 5 |
| Broccoli | Transplant outdoors (spring) | Apr 6 – May 5 |
| Broccoli | Start seeds indoors (fall) | Jun 21 – Jul 1 |
| Broccoli | Transplant outdoors (fall) | Jul 21 – Aug 1 |
| Cabbage | Start seeds indoors (spring) | Feb 20 – Mar 20 |
| Cabbage | Transplant outdoors (spring) | Mar 20 – Apr 20 |
| Cabbage | Start seeds indoors (fall) | Jun 11 – Jul 11 |
| Cabbage | Transplant outdoors (fall) | Jul 11 – Aug 11 |
| Leaf lettuce | Sow outdoors (spring) | Mar 20 – Jun 5 |
| Leaf lettuce | Sow outdoors (fall) | Jul 11 – Aug 27 |
| Spinach | Sow outdoors (spring) | Mar 13 – Apr 26 |
| Spinach | Sow outdoors (fall) | Jul 28 – Sep 1 |
| Radishes | Sow outdoors (spring) | Mar 20 – May 10 |
| Radishes | Sow outdoors (fall) | Jul 11 – Sep 11 |
| Kale | Sow outdoors (spring) | Apr 6 – Apr 26 |
| Kale | Sow outdoors (fall) | Jul 4 – Aug 11 |
| Carrots | Sow outdoors (spring) | Apr 20 – Jun 5 |
| Carrots | Sow outdoors (fall) | Jun 11 – Jul 27 |
| Garlic | Plant outdoors (fall) | Oct 11 – Nov 11 |
Where these dates come from
ZIP code 46242 is matched to the NOAA station Indianapolis Se Side, IN, 9 km away, at 845 ft elevation (114 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Indianapolis Se Side, IN (used) | 845 ft | Apr 20 | Oct 21 |
| Castleton 2 S, IN | 824 ft | Apr 18 | Oct 26 |
| Indianapolis Eagle Creek Ap, IN | 823 ft | Apr 12 | Oct 29 |
| Indianapolis, IN | 790 ft | Apr 15 | Oct 26 |
Frost dates near Indianapolis
- Indianapolis, IN 46209 · last Apr 20, first Oct 21
- Beech Grove, IN 46107 · last Apr 20, first Oct 21
- Greenwood, IN 46142 · last Apr 15, first Oct 26
- West Newton, IN 46183 · last Apr 15, first Oct 26
- New Palestine, IN 46163 · last Apr 20, first Oct 21
- Carmel, IN 46032 · last Apr 21, first Oct 21
- Camby, IN 46113 · last Apr 15, first Oct 26
- Fishers, IN 46038 · last Apr 21, first Oct 21
Frequently asked questions
- When is the last frost in Indianapolis, IN?
- For ZIP code 46242, the average last spring frost (32°F) is April 20, based on NOAA 1991-2020 climate normals for the Indianapolis Se Side, IN weather station. There is a 1-in-10 chance of a frost after May 5.
- When is the first frost in Indianapolis, IN?
- The average first fall frost (32°F) is October 21. There is a 1-in-10 chance of frost by October 7, so tender plants are at risk from that point on.
- How long is the growing season in 46242?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 183 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.