USDA Hardiness Zone 5a
Frost Dates for 59063 — Park City, Montana
NOAA 1991–2020 normals from Joliet, MT (3,838 ft), 11 miles south.
Updated
In Park City, the last spring frost (32°F) is around May 29 in half of years and has passed by June 17 in nine years out of ten. The first fall frost comes around September 15, as early as September 1 one year in ten, leaving a typical freeze-free season of 107 days (NOAA, Joliet, MT).
- Last spring frost
- May 29
- First fall frost
- September 15
- Growing season
- 107 days
- Hardiness zone
- 5a
50% probability
50% probability
freeze-free, 50%
-20 to -15°F (-28.9 to -26.1°C) coldest night
- First snow
- October 11
- Last snow
- April 19
- Winters with snow
- 100%
- Snow per year
- 50.9"
median, 1991–2020
median, 1991–2020
29 of 29 observed
NOAA normal
Frost risk by date in Park City
Half of springs at Joliet, MT see their last 32°F night by May 29; only one in ten is past it by May 14, and one in ten still has one after June 17. Planting tender crops after June 4 leaves a 30% risk of a frost on them, after June 9 20%, and after June 17 10%. The 19 days between the even-odds date and the one-in-ten date is wider than at 78% of the 68 Montana stations behind this site's ZIP pages.
In fall the first 32°F night comes by September 15 in half of years, as early as September 1 one year in ten, and holds off past October 1 one year in ten. A hard freeze of 28°F follows 11 days later, around September 26; in spring the one-in-ten date for 28°F is May 31, 17 days before the 32°F one. The freeze-free season lasts 107 days in a typical year, shorter than at 84% of the 68 Montana stations; it reaches 127 days one year in ten and falls short of 86 one year in ten. On average 185 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 13, and return around September 4. Severe cold of 16°F or below comes every winter, usually between October 27 and April 10.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 30 | Jun 3 | Jun 7 | Jun 10 | Jun 13 | Jun 17 | Jun 20 | Jun 25 | Jun 30 |
| 32°F | May 14 | May 19 | May 22 | May 26 | May 29 | Jun 1 | Jun 4 | Jun 9 | Jun 17 |
| 28°F | May 1 | May 4 | May 8 | May 10 | May 13 | May 16 | May 19 | May 24 | May 31 |
| 24°F | Apr 17 | Apr 22 | Apr 26 | Apr 29 | Apr 30 | May 3 | May 6 | May 9 | May 14 |
| 20°F | Apr 6 | Apr 10 | Apr 14 | Apr 17 | Apr 20 | Apr 24 | Apr 27 | Apr 30 | May 5 |
| 16°F | Mar 24 | Mar 31 | Apr 3 | Apr 6 | Apr 10 | Apr 13 | Apr 17 | Apr 21 | Apr 28 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Aug 22 | Aug 27 | Aug 30 | Sep 1 | Sep 4 | Sep 6 | Sep 9 | Sep 13 | Sep 17 |
| 32°F | Sep 1 | Sep 5 | Sep 9 | Sep 11 | Sep 15 | Sep 17 | Sep 21 | Sep 25 | Oct 1 |
| 28°F | Sep 11 | Sep 17 | Sep 20 | Sep 24 | Sep 26 | Sep 29 | Oct 1 | Oct 4 | Oct 9 |
| 24°F | Sep 22 | Sep 27 | Sep 30 | Oct 2 | Oct 5 | Oct 8 | Oct 12 | Oct 16 | Oct 21 |
| 20°F | Oct 1 | Oct 5 | Oct 10 | Oct 14 | Oct 17 | Oct 20 | Oct 24 | Oct 28 | Nov 1 |
| 16°F | Oct 10 | Oct 16 | Oct 20 | Oct 24 | Oct 27 | Oct 31 | Nov 3 | Nov 7 | Nov 12 |
Freeze probabilities 1991–2020 at Joliet, MT, 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 59063 →Compare Park City with another place →
Weather by month in Park City
July is the warmest month at Joliet, MT, averaging 86°F by day and 50°F at night; January is the coldest at 36°F and 10°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 42% of years.
Warmth for growing adds up to 1,788 growing degree days a year (base 50°F), fewer than at 60% of the 68 Montana stations. 25% of them (455) have built up by the end of June, and July adds the most, 552. Precipitation totals 14.6 inches a year, most in May (2.7") and least in January (0.5"); May to September bring 54% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 36 | 10 | 0.5 | 100% | 29 | 0 |
| Feb | 39 | 12 | 0.6 | 100% | 26 | 1 |
| Mar | 49 | 19 | 0.8 | 100% | 27 | 3 |
| Apr | 57 | 27 | 1.9 | 100% | 20 | 20 |
| May | 66 | 36 | 2.7 | 100% | 7 | 121 |
| Jun | 76 | 44 | 2.1 | 42% | <1 | 310 |
| Jul | 86 | 50 | 0.9 | 0% | 0 | 552 |
| Aug | 84 | 48 | 0.9 | 10% | <1 | 501 |
| Sep | 74 | 39 | 1.3 | 89% | 3 | 230 |
| Oct | 59 | 29 | 1.6 | 100% | 17 | 47 |
| Nov | 45 | 19 | 0.7 | 100% | 26 | 4 |
| Dec | 36 | 11 | 0.6 | 100% | 29 | 0 |
Monthly normals 1991–2020 at Joliet, MT (3,838 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, Columbus, MT, 15 miles west of Park City and 236 feet lower, has a last frost 2 days earlier (May 27), a first frost 1 day earlier (September 14), a season 1 day longer.
When it snows in Park City, Montana
The first measurable snow (0.1 inch or more) in Park City usually arrives around October 11, and the last of the season around April 19. Those are the middle dates across the winters of 1991–2020 at Joliet, MT, 10.6 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 40 days after the last snow.
Planting calendar for 59063
| When | What to do |
|---|---|
| March 20 – April 3 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| April 3 – April 17 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| May 1 – May 15 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 29 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by June 23 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 1 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| September 15 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 59063 is 11 miles from Joliet, MT, which stands at 3,838 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station; its figures are presented in full for 59041 (Joliet). The 2023 USDA Plant Hardiness Zone Map lists ZIP 59063 in zone 5a, the band where the coldest night of the year averaged -20 to -15°F (-28.9 to -26.1°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.