Frost dates for 48197Ypsilanti, MI
The average last spring frost in Ypsilanti is May 5 and the average first fall frost is October 10, giving a typical growing season of about 157 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 5
- Average first fall frost
- Oct 10
- Growing season
- 157 days
Safer after May 20 (1-in-10 risk)
Possible by Sep 28 (1-in-10 risk)
Last frost typically in 183 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 1 · May 15 · May 29 | Sep 18 · Oct 1 · Oct 12 | 137 days | 100% |
| Frost / freeze (32°F) | Apr 21 · May 5 · May 20 | Sep 28 · Oct 10 · Oct 24 | 157 days | 100% |
| Hard freeze (28°F) | Apr 10 · Apr 24 · May 11 | Oct 7 · Oct 23 · Nov 6 | 180 days | 100% |
Planting calendar for Ypsilanti
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 4 – Jun 10 |
| Tomatoes | Transplant outdoors | May 21 – Jun 20 |
| Peppers | Start seeds indoors | Apr 4 – May 5 |
| Peppers | Transplant outdoors | Jun 4 – Jul 5 |
| Eggplant | Start seeds indoors | Apr 21 – May 20 |
| Eggplant | Transplant outdoors | Jun 4 – Jul 5 |
| Cucumbers | Sow outdoors | Jun 4 – Jun 30 |
| Summer squash | Sow outdoors | May 21 – Jul 5 |
| Winter squash & pumpkins | Sow outdoors | Jun 4 – Jul 5 |
| Snap beans | Sow outdoors | May 21 – Jul 23 |
| Sweet corn | Sow outdoors | May 21 – Jun 20 |
| Watermelon & cantaloupe | Sow outdoors | Jun 4 – Jul 5 |
| Okra | Sow outdoors | May 28 – Jun 20 |
| Peas | Sow outdoors (spring) | Apr 4 – May 20 |
| Potatoes | Plant outdoors (spring) | Apr 4 – Jun 4 |
| Onions | Start seeds indoors (spring) | Feb 21 – Mar 20 |
| Onions | Transplant outdoors (spring) | Apr 21 – May 20 |
| Broccoli | Start seeds indoors (spring) | Mar 17 – Apr 20 |
| Broccoli | Transplant outdoors (spring) | Apr 21 – May 20 |
| Broccoli | Start seeds indoors (fall) | Jun 10 – Jun 20 |
| Broccoli | Transplant outdoors (fall) | Jul 10 – Jul 21 |
| Cabbage | Start seeds indoors (spring) | Mar 7 – Apr 4 |
| Cabbage | Transplant outdoors (spring) | Apr 4 – May 5 |
| Cabbage | Start seeds indoors (fall) | May 31 – Jun 30 |
| Cabbage | Transplant outdoors (fall) | Jun 30 – Jul 31 |
| Leaf lettuce | Sow outdoors (spring) | Apr 4 – Jun 20 |
| Leaf lettuce | Sow outdoors (fall) | Jun 30 – Aug 16 |
| Spinach | Sow outdoors (spring) | Mar 28 – May 11 |
| Spinach | Sow outdoors (fall) | Jul 17 – Aug 21 |
| Radishes | Sow outdoors (spring) | Apr 4 – May 25 |
| Radishes | Sow outdoors (fall) | Jun 30 – Aug 31 |
| Kale | Sow outdoors (spring) | Apr 21 – May 11 |
| Kale | Sow outdoors (fall) | Jun 23 – Jul 31 |
| Carrots | Sow outdoors (spring) | May 5 – Jun 20 |
| Carrots | Sow outdoors (fall) | May 31 – Jul 16 |
| Garlic | Plant outdoors (fall) | Sep 30 – Oct 31 |
Where these dates come from
ZIP code 48197 is matched to the NOAA station Ann Arbor Se, MI, 5 km away, at 832 ft elevation (74 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Ann Arbor Se, MI (used) | 832 ft | May 5 | Oct 10 |
| Ann Arbor U Of Mich, MI | 813 ft | May 3 | Oct 13 |
| Detroit Willow Run Ap, MI | 777 ft | Apr 24 | Oct 24 |
| Ann Arbor Muni Ap, MI | 839 ft | May 8 | Oct 4 |
Frost dates near Ypsilanti
- Ypsilanti, MI 48198 · last Apr 24, first Oct 24
- Ann Arbor, MI 48108 · last May 5, first Oct 10
- Whittaker, MI 48190 · last May 3, first Oct 10
- Belleville, MI 48112 · last Apr 24, first Oct 24
- Willis, MI 48191 · last May 3, first Oct 10
- Saline, MI 48176 · last May 2, first Oct 11
- Canton, MI 48188 · last Apr 24, first Oct 24
- Milan, MI 48160 · last May 3, first Oct 10
Frequently asked questions
- When is the last frost in Ypsilanti, MI?
- For ZIP code 48197, the average last spring frost (32°F) is May 5, based on NOAA 1991-2020 climate normals for the Ann Arbor Se, MI weather station. There is a 1-in-10 chance of a frost after May 20.
- When is the first frost in Ypsilanti, MI?
- The average first fall frost (32°F) is October 10. There is a 1-in-10 chance of frost by September 28, so tender plants are at risk from that point on.
- How long is the growing season in 48197?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 157 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.