Frost dates for 53046Lannon, WI
The average last spring frost in Lannon is May 6 and the average first fall frost is October 8, giving a typical growing season of about 154 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 6
- Average first fall frost
- Oct 8
- Growing season
- 154 days
Safer after May 25 (1-in-10 risk)
Possible by Sep 26 (1-in-10 risk)
Last frost typically in 185 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 2 · May 19 · Jun 3 | Sep 13 · Sep 29 · Oct 11 | 132 days | 100% |
| Frost / freeze (32°F) | Apr 22 · May 6 · May 25 | Sep 26 · Oct 8 · Oct 24 | 154 days | 100% |
| Hard freeze (28°F) | Apr 9 · Apr 24 · May 12 | Oct 4 · Oct 20 · Nov 3 | 178 days | 100% |
Planting calendar for Lannon
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 5 – Jun 11 |
| Tomatoes | Transplant outdoors | May 22 – Jun 18 |
| Peppers | Start seeds indoors | Apr 5 – May 6 |
| Peppers | Transplant outdoors | Jun 5 – Jul 6 |
| Eggplant | Start seeds indoors | Apr 22 – May 21 |
| Eggplant | Transplant outdoors | Jun 5 – Jul 6 |
| Cucumbers | Sow outdoors | Jun 5 – Jun 28 |
| Summer squash | Sow outdoors | May 22 – Jul 6 |
| Winter squash & pumpkins | Sow outdoors | Jun 5 – Jul 6 |
| Snap beans | Sow outdoors | May 22 – Jul 21 |
| Sweet corn | Sow outdoors | May 22 – Jun 18 |
| Watermelon & cantaloupe | Sow outdoors | Jun 5 – Jul 6 |
| Okra | Sow outdoors | May 29 – Jun 21 |
| Peas | Sow outdoors (spring) | Apr 5 – May 21 |
| Potatoes | Plant outdoors (spring) | Apr 5 – Jun 5 |
| Onions | Start seeds indoors (spring) | Feb 22 – Mar 21 |
| Onions | Transplant outdoors (spring) | Apr 22 – May 21 |
| Broccoli | Start seeds indoors (spring) | Mar 18 – Apr 21 |
| Broccoli | Transplant outdoors (spring) | Apr 22 – May 21 |
| Broccoli | Start seeds indoors (fall) | Jun 8 – Jun 18 |
| Broccoli | Transplant outdoors (fall) | Jul 8 – Jul 19 |
| Cabbage | Start seeds indoors (spring) | Mar 8 – Apr 5 |
| Cabbage | Transplant outdoors (spring) | Apr 5 – May 6 |
| Cabbage | Start seeds indoors (fall) | May 29 – Jun 28 |
| Cabbage | Transplant outdoors (fall) | Jun 28 – Jul 29 |
| Leaf lettuce | Sow outdoors (spring) | Apr 5 – Jun 21 |
| Leaf lettuce | Sow outdoors (fall) | Jun 28 – Aug 14 |
| Spinach | Sow outdoors (spring) | Mar 29 – May 12 |
| Spinach | Sow outdoors (fall) | Jul 15 – Aug 19 |
| Radishes | Sow outdoors (spring) | Apr 5 – May 26 |
| Radishes | Sow outdoors (fall) | Jun 28 – Aug 29 |
| Kale | Sow outdoors (spring) | Apr 22 – May 12 |
| Kale | Sow outdoors (fall) | Jun 21 – Jul 29 |
| Carrots | Sow outdoors (spring) | May 6 – Jun 21 |
| Carrots | Sow outdoors (fall) | May 29 – Jul 14 |
| Garlic | Plant outdoors (fall) | Sep 28 – Oct 29 |
Where these dates come from
ZIP code 53046 is matched to the NOAA station Germantown, WI, 10.5 km away, at 850 ft elevation (36 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Germantown, WI (used) | 850 ft | May 6 | Oct 8 |
| Richfield 3 Ssw, WI | 984 ft | Apr 30 | Oct 16 |
| Brookfield Wwtp, WI | 830 ft | Apr 30 | Oct 14 |
| Mt Mary College, WI | 715 ft | Apr 26 | Oct 18 |
Frost dates near Lannon
- Menomonee Falls, WI 53051 · last May 6, first Oct 8
- Sussex, WI 53089 · last May 6, first Oct 8
- Colgate, WI 53017 · last May 6, first Oct 8
- Germantown, WI 53022 · last May 6, first Oct 8
- Butler, WI 53007 · last Apr 26, first Oct 18
- Brookfield, WI 53045 · last May 1, first Oct 13
- Milwaukee, WI 53224 · last Apr 26, first Oct 18
- Hubertus, WI 53033 · last May 6, first Oct 8
Frequently asked questions
- When is the last frost in Lannon, WI?
- For ZIP code 53046, the average last spring frost (32°F) is May 6, based on NOAA 1991-2020 climate normals for the Germantown, WI weather station. There is a 1-in-10 chance of a frost after May 25.
- When is the first frost in Lannon, WI?
- The average first fall frost (32°F) is October 8. There is a 1-in-10 chance of frost by September 26, so tender plants are at risk from that point on.
- How long is the growing season in 53046?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 154 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.