Frost dates for 53078Rubicon, WI
The average last spring frost in Rubicon is May 8 and the average first fall frost is October 3, giving a typical growing season of about 148 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 8
- Average first fall frost
- Oct 3
- Growing season
- 148 days
Safer after May 24 (1-in-10 risk)
Possible by Sep 20 (1-in-10 risk)
Last frost typically in 186 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 20 · Jun 2 | Sep 12 · Sep 25 · Oct 6 | 128 days | 100% |
| Frost / freeze (32°F) | Apr 24 · May 8 · May 24 | Sep 20 · Oct 3 · Oct 16 | 148 days | 100% |
| Hard freeze (28°F) | Apr 11 · Apr 27 · May 12 | Sep 30 · Oct 15 · Oct 30 | 171 days | 100% |
Planting calendar for Rubicon
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 13 |
| 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 23 |
| Summer squash | Sow outdoors | May 24 – Jul 8 |
| Winter squash & pumpkins | Sow outdoors | Jun 7 – Jul 8 |
| Snap beans | Sow outdoors | May 24 – Jul 16 |
| Sweet corn | Sow outdoors | May 24 – Jun 13 |
| 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 3 – Jun 13 |
| Broccoli | Transplant outdoors (fall) | Jul 3 – Jul 14 |
| Cabbage | Start seeds indoors (spring) | Mar 10 – Apr 7 |
| Cabbage | Transplant outdoors (spring) | Apr 7 – May 8 |
| Cabbage | Start seeds indoors (fall) | May 24 – Jun 23 |
| Cabbage | Transplant outdoors (fall) | Jun 23 – Jul 24 |
| Leaf lettuce | Sow outdoors (spring) | Apr 7 – Jun 23 |
| Leaf lettuce | Sow outdoors (fall) | Jun 23 – Aug 9 |
| Spinach | Sow outdoors (spring) | Mar 31 – May 14 |
| Spinach | Sow outdoors (fall) | Jul 10 – Aug 14 |
| Radishes | Sow outdoors (spring) | Apr 7 – May 28 |
| Radishes | Sow outdoors (fall) | Jun 23 – Aug 24 |
| Kale | Sow outdoors (spring) | Apr 24 – May 14 |
| Kale | Sow outdoors (fall) | Jun 16 – Jul 24 |
| Carrots | Sow outdoors (spring) | May 8 – Jun 23 |
| Carrots | Sow outdoors (fall) | May 24 – Jul 9 |
| Garlic | Plant outdoors (fall) | Sep 23 – Oct 24 |
Where these dates come from
ZIP code 53078 is matched to the NOAA station Hartford Wwtp, WI, 4 km away, at 961 ft elevation (36 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Hartford Wwtp, WI (used) | 961 ft | May 8 | Oct 3 |
| Hustisford Wwtp, WI | 864 ft | Apr 28 | Oct 10 |
| Slinger Wwtp, WI | 1,029 ft | May 5 | Oct 5 |
| Horicon Wwtp, WI | 881 ft | May 1 | Oct 10 |
Frost dates near Rubicon
- Neosho, WI 53059 · last May 8, first Oct 3
- Hartford, WI 53027 · last May 8, first Oct 3
- Woodland, WI 53099 · last May 8, first Oct 3
- Iron Ridge, WI 53035 · last May 1, first Oct 10
- Ashippun, WI 53003 · last Apr 30, first Oct 12
- Hustisford, WI 53034 · last May 1, first Oct 10
- Slinger, WI 53086 · last May 8, first Oct 3
- Lebanon, WI 53047 · last Apr 28, first Oct 12
Frequently asked questions
- When is the last frost in Rubicon, WI?
- For ZIP code 53078, the average last spring frost (32°F) is May 8, based on NOAA 1991-2020 climate normals for the Hartford Wwtp, WI weather station. There is a 1-in-10 chance of a frost after May 24.
- When is the first frost in Rubicon, WI?
- The average first fall frost (32°F) is October 3. 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 53078?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 148 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.