Frost dates for 84078Vernal, UT
The average last spring frost in Vernal is May 7 and the average first fall frost is October 6, giving a typical growing season of about 150 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 7
- Average first fall frost
- Oct 6
- Growing season
- 150 days
Safer after May 28 (1-in-10 risk)
Possible by Sep 23 (1-in-10 risk)
Last frost typically in 192 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 23 · Jun 9 | Sep 13 · Sep 27 · Oct 8 | 126 days | 100% |
| Frost / freeze (32°F) | Apr 24 · May 7 · May 28 | Sep 23 · Oct 6 · Oct 20 | 150 days | 100% |
| Hard freeze (28°F) | Apr 11 · Apr 25 · May 11 | Oct 3 · Oct 18 · Oct 30 | 174 days | 100% |
Planting calendar for Vernal
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 16 |
| 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 – Jun 26 |
| Summer squash | Sow outdoors | May 23 – Jul 7 |
| Winter squash & pumpkins | Sow outdoors | Jun 6 – Jul 7 |
| Snap beans | Sow outdoors | May 23 – Jul 19 |
| Sweet corn | Sow outdoors | May 23 – Jun 16 |
| 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 6 – Jun 16 |
| Broccoli | Transplant outdoors (fall) | Jul 6 – Jul 17 |
| Cabbage | Start seeds indoors (spring) | Mar 9 – Apr 6 |
| Cabbage | Transplant outdoors (spring) | Apr 6 – May 7 |
| Cabbage | Start seeds indoors (fall) | May 27 – Jun 26 |
| Cabbage | Transplant outdoors (fall) | Jun 26 – Jul 27 |
| Leaf lettuce | Sow outdoors (spring) | Apr 6 – Jun 22 |
| Leaf lettuce | Sow outdoors (fall) | Jun 26 – Aug 12 |
| Spinach | Sow outdoors (spring) | Mar 30 – May 13 |
| Spinach | Sow outdoors (fall) | Jul 13 – Aug 17 |
| Radishes | Sow outdoors (spring) | Apr 6 – May 27 |
| Radishes | Sow outdoors (fall) | Jun 26 – Aug 27 |
| Kale | Sow outdoors (spring) | Apr 23 – May 13 |
| Kale | Sow outdoors (fall) | Jun 19 – Jul 27 |
| Carrots | Sow outdoors (spring) | May 7 – Jun 22 |
| Carrots | Sow outdoors (fall) | May 27 – Jul 12 |
| Garlic | Plant outdoors (fall) | Sep 26 – Oct 27 |
Where these dates come from
ZIP code 84078 is matched to the NOAA station Vernal, UT, 1 km away, at 5,345 ft elevation (45 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Vernal, UT (used) | 5,345 ft | May 7 | Oct 6 |
| Vernal Municipal Ap, UT | 5,260 ft | May 6 | Oct 7 |
| Maeser 9Nw, UT | 6,448 ft | May 15 | Oct 5 |
| Jensen, UT | 4,736 ft | May 20 | Sep 25 |
Frost dates near Vernal
- Vernal, UT 84079 · last May 7, first Oct 6
- Jensen, UT 84035 · last May 20, first Sep 25
- Lapoint, UT 84039 · last May 7, first Oct 6
- Tridell, UT 84076 · last May 19, first Sep 29
- Randlett, UT 84063 · last May 2, first Oct 3
- Fort Duchesne, UT 84026 · last May 19, first Oct 2
- Whiterocks, UT 84085 · last May 19, first Sep 29
- Neola, UT 84053 · last May 19, first Sep 29
Frequently asked questions
- When is the last frost in Vernal, UT?
- For ZIP code 84078, the average last spring frost (32°F) is May 7, based on NOAA 1991-2020 climate normals for the Vernal, UT weather station. There is a 1-in-10 chance of a frost after May 28.
- When is the first frost in Vernal, UT?
- The average first fall frost (32°F) is October 6. There is a 1-in-10 chance of frost by September 23, so tender plants are at risk from that point on.
- How long is the growing season in 84078?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 150 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.