Frost dates for 48113Ann Arbor, MI
The average last spring frost in Ann Arbor is May 8 and the average first fall frost is October 4, giving a typical growing season of about 147 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 8
- Average first fall frost
- Oct 4
- Growing season
- 147 days
Safer after May 26 (1-in-10 risk)
Possible by Sep 20 (1-in-10 risk)
Last frost typically in 203 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) | May 5 · May 24 · Jun 10 | Sep 10 · Sep 24 · Oct 6 | 122 days | 100% |
| Frost / freeze (32°F) | Apr 23 · May 8 · May 26 | Sep 20 · Oct 4 · Oct 17 | 147 days | 100% |
| Hard freeze (28°F) | Apr 12 · Apr 27 · May 15 | Sep 30 · Oct 16 · Oct 31 | 169 days | 100% |
Planting calendar for Ann Arbor
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 | Apr 7 – Jun 13 |
| Tomatoes | Transplant outdoors | May 24 – Jun 14 |
| Peppers | Start seeds indoors | Apr 7 – May 8 |
| Peppers | Transplant outdoors | Jun 7 – Jul 8 |
| Eggplant | Start seeds indoors | Apr 24 – May 23 |
| Eggplant | Transplant outdoors | Jun 7 – Jul 8 |
| Cucumbers | Sow outdoors | Jun 7 – Jun 24 |
| Summer squash | Sow outdoors | May 24 – Jul 8 |
| Winter squash & pumpkins | Sow outdoors | Jun 7 – Jul 8 |
| Snap beans | Sow outdoors | May 24 – Jul 17 |
| Sweet corn | Sow outdoors | May 24 – Jun 14 |
| Watermelon & cantaloupe | Sow outdoors | Jun 7 – Jul 8 |
| Okra | Sow outdoors | May 31 – Jun 23 |
| Peas | Sow outdoors (spring) | Apr 7 – May 23 |
| Potatoes | Plant outdoors (spring) | Apr 7 – Jun 7 |
| Onions | Start seeds indoors (spring) | Feb 24 – Mar 23 |
| Onions | Transplant outdoors (spring) | Apr 24 – May 23 |
| Broccoli | Start seeds indoors (spring) | Mar 20 – Apr 23 |
| Broccoli | Transplant outdoors (spring) | Apr 24 – May 23 |
| Broccoli | Start seeds indoors (fall) | Jun 4 – Jun 14 |
| Broccoli | Transplant outdoors (fall) | Jul 4 – Jul 15 |
| Cabbage | Start seeds indoors (spring) | Mar 10 – Apr 7 |
| Cabbage | Transplant outdoors (spring) | Apr 7 – May 8 |
| Cabbage | Start seeds indoors (fall) | May 25 – Jun 24 |
| Cabbage | Transplant outdoors (fall) | Jun 24 – Jul 25 |
| Leaf lettuce | Sow outdoors (spring) | Apr 7 – Jun 23 |
| Leaf lettuce | Sow outdoors (fall) | Jun 24 – Aug 10 |
| Spinach | Sow outdoors (spring) | Mar 31 – May 14 |
| Spinach | Sow outdoors (fall) | Jul 11 – Aug 15 |
| Radishes | Sow outdoors (spring) | Apr 7 – May 28 |
| Radishes | Sow outdoors (fall) | Jun 24 – Aug 25 |
| Kale | Sow outdoors (spring) | Apr 24 – May 14 |
| Kale | Sow outdoors (fall) | Jun 17 – Jul 25 |
| Carrots | Sow outdoors (spring) | May 8 – Jun 23 |
| Carrots | Sow outdoors (fall) | May 25 – Jul 10 |
| Garlic | Plant outdoors (fall) | Sep 24 – Oct 25 |
Where these dates come from
ZIP code 48113 is matched to the NOAA station Ann Arbor Muni Ap, MI, 8.3 km away, at 839 ft elevation (165 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Ann Arbor Muni Ap, MI (used) | 839 ft | May 8 | Oct 4 |
| Saline Wwtp, MI | 750 ft | May 2 | Oct 11 |
| Ann Arbor Se, MI | 832 ft | May 5 | Oct 10 |
| Saline 4Sw, MI | 840 ft | May 2 | Oct 11 |
Frost dates near Ann Arbor
- Ann Arbor, MI 48106 · last May 8, first Oct 4
- Saline, MI 48176 · last May 2, first Oct 11
- Bridgewater, MI 48115 · last Apr 30, first Oct 14
- Dexter, MI 48130 · last Apr 30, first Oct 12
- Ypsilanti, MI 48197 · last May 5, first Oct 10
- Chelsea, MI 48118 · last Apr 30, first Oct 12
- Manchester, MI 48158 · last Apr 30, first Oct 14
- Whitmore Lake, MI 48189 · last May 5, first Oct 13
Frequently asked questions
- When is the last frost in Ann Arbor, MI?
- For ZIP code 48113, the average last spring frost (32°F) is May 8, based on NOAA 1991-2020 climate normals for the Ann Arbor Muni Ap, MI weather station. There is a 1-in-10 chance of a frost after May 26.
- When is the first frost in Ann Arbor, MI?
- The average first fall frost (32°F) is October 4. There is a 1-in-10 chance of frost by September 20, so tender plants are at risk from that point on.
- How long is the growing season in 48113?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 147 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.