Frost dates for 84029Grantsville, UT
The average last spring frost in Grantsville is May 2 and the average first fall frost is October 14, giving a typical growing season of about 164 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 2
- Average first fall frost
- Oct 14
- Growing season
- 164 days
Safer after May 19 (1-in-10 risk)
Possible by Sep 30 (1-in-10 risk)
Last frost typically in 187 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 16 · Jun 5 | Sep 21 · Oct 4 · Oct 17 | 140 days | 100% |
| Frost / freeze (32°F) | Apr 17 · May 2 · May 19 | Sep 30 · Oct 14 · Oct 27 | 164 days | 100% |
| Hard freeze (28°F) | Mar 31 · Apr 17 · May 5 | Oct 8 · Oct 25 · Nov 8 | 189 days | 100% |
Planting calendar for Grantsville
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 1 – Jun 7 |
| Tomatoes | Transplant outdoors | May 18 – Jun 24 |
| Peppers | Start seeds indoors | Apr 1 – May 2 |
| Peppers | Transplant outdoors | Jun 1 – Jul 2 |
| Eggplant | Start seeds indoors | Apr 18 – May 17 |
| Eggplant | Transplant outdoors | Jun 1 – Jul 2 |
| Cucumbers | Sow outdoors | Jun 1 – Jul 4 |
| Summer squash | Sow outdoors | May 18 – Jul 2 |
| Winter squash & pumpkins | Sow outdoors | Jun 1 – Jul 2 |
| Snap beans | Sow outdoors | May 18 – Jul 27 |
| Sweet corn | Sow outdoors | May 18 – Jun 24 |
| Watermelon & cantaloupe | Sow outdoors | Jun 1 – Jul 2 |
| Okra | Sow outdoors | May 25 – Jun 17 |
| Peas | Sow outdoors (spring) | Apr 1 – May 17 |
| Potatoes | Plant outdoors (spring) | Apr 1 – Jun 1 |
| Onions | Start seeds indoors (spring) | Feb 18 – Mar 17 |
| Onions | Transplant outdoors (spring) | Apr 18 – May 17 |
| Broccoli | Start seeds indoors (spring) | Mar 14 – Apr 17 |
| Broccoli | Transplant outdoors (spring) | Apr 18 – May 17 |
| Broccoli | Start seeds indoors (fall) | Jun 14 – Jun 24 |
| Broccoli | Transplant outdoors (fall) | Jul 14 – Jul 25 |
| Cabbage | Start seeds indoors (spring) | Mar 4 – Apr 1 |
| Cabbage | Transplant outdoors (spring) | Apr 1 – May 2 |
| Cabbage | Start seeds indoors (fall) | Jun 4 – Jul 4 |
| Cabbage | Transplant outdoors (fall) | Jul 4 – Aug 4 |
| Leaf lettuce | Sow outdoors (spring) | Apr 1 – Jun 17 |
| Leaf lettuce | Sow outdoors (fall) | Jul 4 – Aug 20 |
| Spinach | Sow outdoors (spring) | Mar 25 – May 8 |
| Spinach | Sow outdoors (fall) | Jul 21 – Aug 25 |
| Radishes | Sow outdoors (spring) | Apr 1 – May 22 |
| Radishes | Sow outdoors (fall) | Jul 4 – Sep 4 |
| Kale | Sow outdoors (spring) | Apr 18 – May 8 |
| Kale | Sow outdoors (fall) | Jun 27 – Aug 4 |
| Carrots | Sow outdoors (spring) | May 2 – Jun 17 |
| Carrots | Sow outdoors (fall) | Jun 4 – Jul 20 |
| Garlic | Plant outdoors (fall) | Oct 4 – Nov 4 |
Where these dates come from
ZIP code 84029 is matched to the NOAA station Grantsville 2W, UT, 3.9 km away, at 4,550 ft elevation (252 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Grantsville 2W, UT (used) | 4,550 ft | May 2 | Oct 14 |
| Tooele, UT | 4,944 ft | May 2 | Oct 16 |
| Garfield, UT | 4,298 ft | Apr 3 | Nov 4 |
| Johnson Pass, UT | 5,580 ft | May 15 | Oct 5 |
Frost dates near Grantsville
- Tooele, UT 84074 · last May 2, first Oct 16
- Stockton, UT 84071 · last May 2, first Oct 16
- Rush Valley, UT 84069 · last May 15, first Oct 5
- Bingham Canyon, UT 84006 · last May 2, first Oct 16
- Magna, UT 84044 · last Apr 8, first Oct 31
- West Jordan, UT 84081 · last Apr 29, first Oct 22
- Herriman, UT 84096 · last May 2, first Oct 16
- Salt Lake City, UT 84118 · last Apr 18, first Oct 22
Frequently asked questions
- When is the last frost in Grantsville, UT?
- For ZIP code 84029, the average last spring frost (32°F) is May 2, based on NOAA 1991-2020 climate normals for the Grantsville 2W, UT weather station. There is a 1-in-10 chance of a frost after May 19.
- When is the first frost in Grantsville, UT?
- The average first fall frost (32°F) is October 14. There is a 1-in-10 chance of frost by September 30, so tender plants are at risk from that point on.
- How long is the growing season in 84029?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 164 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.