Frost dates for 84121Salt Lake City, UT
The average last spring frost in Salt Lake City is May 7 and the average first fall frost is October 14, giving a typical growing season of about 158 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 7
- Average first fall frost
- Oct 14
- Growing season
- 158 days
Safer after May 27 (1-in-10 risk)
Possible by Sep 29 (1-in-10 risk)
Last frost typically in 193 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 8 · May 25 · Jun 11 | Sep 15 · Oct 1 · Oct 15 | 128 days | 100% |
| Frost / freeze (32°F) | Apr 21 · May 7 · May 27 | Sep 29 · Oct 14 · Oct 27 | 158 days | 100% |
| Hard freeze (28°F) | Apr 4 · Apr 21 · May 6 | Oct 11 · Oct 26 · Nov 9 | 188 days | 100% |
Planting calendar for Salt Lake City
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 6 – Jun 12 |
| Tomatoes | Transplant outdoors | May 23 – Jun 24 |
| Peppers | Start seeds indoors | Apr 6 – May 7 |
| Peppers | Transplant outdoors | Jun 6 – Jul 7 |
| Eggplant | Start seeds indoors | Apr 23 – May 22 |
| Eggplant | Transplant outdoors | Jun 6 – Jul 7 |
| Cucumbers | Sow outdoors | Jun 6 – Jul 4 |
| Summer squash | Sow outdoors | May 23 – Jul 7 |
| Winter squash & pumpkins | Sow outdoors | Jun 6 – Jul 7 |
| Snap beans | Sow outdoors | May 23 – Jul 27 |
| Sweet corn | Sow outdoors | May 23 – Jun 24 |
| Watermelon & cantaloupe | Sow outdoors | Jun 6 – Jul 7 |
| Okra | Sow outdoors | May 30 – Jun 22 |
| Peas | Sow outdoors (spring) | Apr 6 – May 22 |
| Potatoes | Plant outdoors (spring) | Apr 6 – Jun 6 |
| Onions | Start seeds indoors (spring) | Feb 23 – Mar 22 |
| Onions | Transplant outdoors (spring) | Apr 23 – May 22 |
| Broccoli | Start seeds indoors (spring) | Mar 19 – Apr 22 |
| Broccoli | Transplant outdoors (spring) | Apr 23 – May 22 |
| Broccoli | Start seeds indoors (fall) | Jun 14 – Jun 24 |
| Broccoli | Transplant outdoors (fall) | Jul 14 – Jul 25 |
| Cabbage | Start seeds indoors (spring) | Mar 9 – Apr 6 |
| Cabbage | Transplant outdoors (spring) | Apr 6 – May 7 |
| Cabbage | Start seeds indoors (fall) | Jun 4 – Jul 4 |
| Cabbage | Transplant outdoors (fall) | Jul 4 – Aug 4 |
| Leaf lettuce | Sow outdoors (spring) | Apr 6 – Jun 22 |
| Leaf lettuce | Sow outdoors (fall) | Jul 4 – Aug 20 |
| Spinach | Sow outdoors (spring) | Mar 30 – May 13 |
| Spinach | Sow outdoors (fall) | Jul 21 – Aug 25 |
| Radishes | Sow outdoors (spring) | Apr 6 – May 27 |
| Radishes | Sow outdoors (fall) | Jul 4 – Sep 4 |
| Kale | Sow outdoors (spring) | Apr 23 – May 13 |
| Kale | Sow outdoors (fall) | Jun 27 – Aug 4 |
| Carrots | Sow outdoors (spring) | May 7 – Jun 22 |
| Carrots | Sow outdoors (fall) | Jun 4 – Jul 20 |
| Garlic | Plant outdoors (fall) | Oct 4 – Nov 4 |
Where these dates come from
ZIP code 84121 is matched to the NOAA station Mtn Dell Dam, UT, 14.7 km away, at 5,420 ft elevation (381 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Mtn Dell Dam, UT (used) | 5,420 ft | May 7 | Oct 14 |
| Cottonwood Weir, UT | 4,986 ft | Apr 29 | Oct 22 |
| Alta, UT | 8,710 ft | Jun 11 | Sep 18 |
| Salt Lake City E Bench, UT | 4,850 ft | Apr 25 | Oct 18 |
Frost dates near Salt Lake City
- Sandy, UT 84092 · last Jun 11, first Sep 18
- Salt Lake City, UT 84117 · last Apr 18, first Oct 22
- Midvale, UT 84047 · last Apr 18, first Oct 22
- South Jordan, UT 84009 · last Apr 18, first Oct 22
- Draper, UT 84020 · last Apr 18, first Oct 22
- West Jordan, UT 84088 · last Apr 18, first Oct 22
- Alpine, UT 84004 · last May 3, first Oct 12
- Riverton, UT 84065 · last Apr 18, first Oct 22
Frequently asked questions
- When is the last frost in Salt Lake City, UT?
- For ZIP code 84121, the average last spring frost (32°F) is May 7, based on NOAA 1991-2020 climate normals for the Mtn Dell Dam, UT weather station. There is a 1-in-10 chance of a frost after May 27.
- When is the first frost in Salt Lake City, UT?
- The average first fall frost (32°F) is October 14. There is a 1-in-10 chance of frost by September 29, so tender plants are at risk from that point on.
- How long is the growing season in 84121?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 158 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.