USDA Hardiness Zone 6a
Frost Dates for 84526 — Helper, Utah
NOAA 1991–2020 normals from Scofield Dam, UT (7,630 ft), 10 miles northwest.
Updated
In Helper, the last spring frost (32°F) is around June 15 in half of years and has passed by July 1 in nine years out of ten. The first fall frost comes around September 12, as early as August 29 one year in ten, leaving a typical freeze-free season of 87 days (NOAA, Scofield Dam, UT).
- Last spring frost
- June 15
- First fall frost
- September 12
- Growing season
- 87 days
- Hardiness zone
- 6a
50% probability
50% probability
freeze-free, 50%
-10 to -5°F (-23.3 to -20.6°C) coldest night
- First snow
- October 6
- Last snow
- May 17
- Winters with snow
- 100%
- Snow per year
- 225.4"
median, 1991–2020
median, 1991–2020
29 of 29 observed
NOAA normal
Frost risk by date in Helper
Half of springs at Scofield Dam, UT see their last 32°F night by June 15; only one in ten is past it by June 2, and one in ten still has one after July 1. Planting tender crops after June 22 leaves a 30% risk of a frost on them, after June 26 20%, and after July 1 10%. The 16 days between the even-odds date and the one-in-ten date is narrower than at 83% of the 66 Utah stations behind this site's ZIP pages.
In fall the first 32°F night comes by September 12 in half of years, as early as August 29 one year in ten, and holds off past September 24 one year in ten. A hard freeze of 28°F follows 9 days later, around September 21; in spring the one-in-ten date for 28°F is June 19, 12 days before the 32°F one. The freeze-free season lasts 87 days in a typical year, shorter than at 98% of the 66 Utah stations; it reaches 106 days one year in ten and falls short of 67 one year in ten. On average 248 nights a year drop to 32°F or below. Severe cold of 16°F or below comes every winter, usually between October 26 and April 20.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | too rare for a date | ||||||||
| 32°F | Jun 2 | Jun 6 | Jun 9 | Jun 13 | Jun 15 | Jun 19 | Jun 22 | Jun 26 | Jul 1 |
| 28°F | May 18 | May 23 | May 28 | May 31 | Jun 3 | Jun 6 | Jun 9 | Jun 13 | Jun 19 |
| 24°F | May 2 | May 7 | May 11 | May 15 | May 19 | May 22 | May 26 | Jun 1 | Jun 8 |
| 20°F | Apr 19 | Apr 23 | Apr 27 | Apr 30 | May 2 | May 5 | May 9 | May 15 | May 23 |
| 16°F | Apr 4 | Apr 9 | Apr 13 | Apr 16 | Apr 20 | Apr 22 | Apr 27 | May 1 | May 6 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | too rare for a date | ||||||||
| 32°F | Aug 29 | Sep 4 | Sep 7 | Sep 9 | Sep 12 | Sep 15 | Sep 17 | Sep 20 | Sep 24 |
| 28°F | Sep 8 | Sep 12 | Sep 16 | Sep 19 | Sep 21 | Sep 24 | Sep 27 | Sep 30 | Oct 5 |
| 24°F | Sep 18 | Sep 23 | Sep 26 | Sep 30 | Oct 2 | Oct 5 | Oct 8 | Oct 12 | Oct 16 |
| 20°F | Sep 28 | Oct 4 | Oct 7 | Oct 10 | Oct 14 | Oct 17 | Oct 20 | Oct 24 | Oct 28 |
| 16°F | Oct 11 | Oct 16 | Oct 20 | Oct 23 | Oct 26 | Oct 28 | Oct 31 | Nov 4 | Nov 9 |
Freeze probabilities 1991–2020 at Scofield Dam, UT, from NOAA NCEI U.S. Climate Normals. Where a temperature is reached in fewer than 99.5% of years, the dates describe only the years that reach it. Not a forecast.
Frost risk on any date in 84526 →Compare Helper with another place →
Compared with the next station
The nearest other station, Scofield-Skyline Mine, UT, 12 miles west of Helper and 1,067 feet higher, has a last frost 2 days earlier (June 13), a first frost 5 days later (September 17), a season 7 days longer.
When it snows in Helper, Utah
The first measurable snow (0.1 inch or more) in Helper usually arrives around October 6, and the last of the season around May 17. Those are the middle dates across the winters of 1991–2020 at Scofield-Skyline Mine, UT, 11.7 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 29 days after the last snow.
Planting calendar for 84526
| When | What to do |
|---|---|
| April 6 – April 20 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| April 20 – May 4 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| May 18 – June 1 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| June 15 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by June 20 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by August 29 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| September 12 onward | Plant garlic, mulch beds, lift tender bulbsGarlic wants a cold spell; bare soil loses structure over winter. |
The weeks before and after the 50% dates are general rules of thumb, not NOAA figures; a seed packet gives the timing for each variety.
Where these figures come from
ZIP 84526 is 10 miles from Scofield Dam, UT, which stands at 7,630 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 84526 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°C) over 1991–2020; a zone describes winter lows, not frost dates.
Hardiness zone and temperature range: USDA Plant Hardiness Zone Map 2023 (USDA-ARS, Oregon State University), ZIP-code listing, unchanged. °C converted from °F by this site.
Thirty-year averages, not a forecast: check the forecast before planting out. How stations are matched and which pages are offered to search engines: methodology.