USDA Hardiness Zone 5b
Frost Dates for 84647 — Mt Pleasant, Utah
NOAA 1991–2020 normals from Moroni, UT (5,580 ft), 8 miles west.
Updated
In Mt Pleasant, the last spring frost (32°F) is around May 26 in half of years and has passed by June 13 in nine years out of ten. The first fall frost comes around September 25, as early as September 9 one year in ten, leaving a typical freeze-free season of 119 days (NOAA, Moroni, UT).
- Last spring frost
- May 26
- First fall frost
- September 25
- Growing season
- 119 days
- Hardiness zone
- 5b
50% probability
50% probability
freeze-free, 50%
-15 to -10°F (-26.1 to -23.3°C) coldest night
- First snow
- November 10
- Last snow
- April 6
- Winters with snow
- 96%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
22 of 23 observed
NOAA normal
Frost risk by date in Mt Pleasant
Half of springs at Moroni, UT see their last 32°F night by May 26; only one in ten is past it by May 10, and one in ten still has one after June 13. Planting tender crops after June 3 leaves a 30% risk of a frost on them, after June 6 20%, and after June 13 10%. The 18 days between the even-odds date and the one-in-ten date is narrower than at 47% of the 66 Utah stations behind this site's ZIP pages.
In fall the first 32°F night comes by September 25 in half of years, as early as September 9 one year in ten, and holds off past October 8 one year in ten. A hard freeze of 28°F follows 10 days later, around October 5; in spring the one-in-ten date for 28°F is May 30, 14 days before the 32°F one. The freeze-free season lasts 119 days in a typical year, shorter than at 77% of the 66 Utah stations; it reaches 141 days one year in ten and falls short of 98 one year in ten. On average 189 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 15 days longer, to about June 10, and return around September 16. Severe cold of 16°F or below comes every winter, usually between November 9 and March 18.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 27 | Jun 1 | Jun 4 | Jun 6 | Jun 10 | Jun 13 | Jun 18 | Jun 22 | Jun 28 |
| 32°F | May 10 | May 15 | May 19 | May 23 | May 26 | May 31 | Jun 3 | Jun 6 | Jun 13 |
| 28°F | Apr 25 | Apr 30 | May 3 | May 7 | May 10 | May 13 | May 16 | May 21 | May 30 |
| 24°F | Apr 11 | Apr 16 | Apr 20 | Apr 24 | Apr 27 | Apr 30 | May 3 | May 6 | May 11 |
| 20°F | Mar 18 | Mar 29 | Apr 2 | Apr 6 | Apr 10 | Apr 14 | Apr 18 | Apr 23 | Apr 29 |
| 16°F | Feb 28 | Mar 5 | Mar 9 | Mar 13 | Mar 18 | Mar 24 | Mar 30 | Apr 4 | Apr 10 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 1 | Sep 5 | Sep 9 | Sep 13 | Sep 16 | Sep 19 | Sep 21 | Sep 24 | Sep 27 |
| 32°F | Sep 9 | Sep 15 | Sep 19 | Sep 22 | Sep 25 | Sep 27 | Sep 30 | Oct 4 | Oct 8 |
| 28°F | Sep 21 | Sep 26 | Sep 29 | Oct 1 | Oct 5 | Oct 7 | Oct 11 | Oct 15 | Oct 20 |
| 24°F | Oct 1 | Oct 6 | Oct 10 | Oct 14 | Oct 17 | Oct 20 | Oct 23 | Oct 26 | Nov 1 |
| 20°F | Oct 13 | Oct 19 | Oct 23 | Oct 26 | Oct 29 | Nov 1 | Nov 4 | Nov 7 | Nov 12 |
| 16°F | Oct 25 | Oct 31 | Nov 3 | Nov 6 | Nov 9 | Nov 12 | Nov 15 | Nov 19 | Nov 24 |
Freeze probabilities 1991–2020 at Moroni, 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 84647 →Compare Mt Pleasant with another place →
Weather by month in Mt Pleasant
July is the warmest month at Moroni, UT, averaging 89°F by day and 52°F at night; January is the coldest at 38°F and 13°F. A freezing night is all but certain in every month from October to May (a 90% chance or more). From July to August the chance of a 32°F night stays under 10% each month. In spring, June still brings one in 37% of years.
Warmth for growing adds up to 2,223 growing degree days a year (base 50°F), fewer than at 73% of the 66 Utah stations. 27% of them (604) have built up by the end of June, and July adds the most, 635.
| Month | High °F | Low °F | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|
| Jan | 38 | 13 | 100% | 30 | 0 |
| Feb | 43 | 18 | 100% | 27 | 0 |
| Mar | 55 | 25 | 100% | 27 | 5 |
| Apr | 62 | 30 | 100% | 20 | 31 |
| May | 71 | 37 | 98% | 7 | 169 |
| Jun | 82 | 44 | 37% | 1 | 398 |
| Jul | 89 | 52 | 0% | 0 | 635 |
| Aug | 87 | 51 | 2% | <1 | 584 |
| Sep | 79 | 42 | 70% | 2 | 323 |
| Oct | 66 | 32 | 100% | 17 | 73 |
| Nov | 52 | 22 | 100% | 27 | 4 |
| Dec | 38 | 13 | 100% | 30 | 0 |
Monthly normals 1991–2020 at Moroni, UT (5,580 ft), NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.
Compared with the next station
The nearest other station, Ephraim, UT, 16 miles southwest of Mt Pleasant, has a last frost 2 days later (May 28), a first frost 5 days earlier (September 20), a season 6 days shorter.
When it snows in Mt Pleasant, Utah
The first measurable snow (0.1 inch or more) in Mt Pleasant usually arrives around November 10, and the last of the season around April 6. Those are the middle dates across the winters of 1991–2020 at Moroni, UT, 8.1 miles away: half of years saw snow earlier, half later. Snow fell in 96% of those winters. The last 32°F night of spring typically comes 50 days after the last snow.
Planting calendar for 84647
| When | What to do |
|---|---|
| March 17 – March 31 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 31 – April 14 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 28 – May 12 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 26 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 3 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 11 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| September 25 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 84647 is 8 miles from Moroni, UT, which stands at 5,580 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 84647 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°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.