USDA Hardiness Zone 6b
Frost Dates for 16875 — Spring Mills, Pennsylvania
NOAA 1991–2020 normals from Millheim, PA (1,120 ft), 6 miles northeast.
Updated
In Spring Mills, the last spring frost (32°F) is around May 5 in half of years and has passed by May 24 in nine years out of ten. The first fall frost comes around October 6, as early as September 25 one year in ten, leaving a typical freeze-free season of 153 days (NOAA, Millheim, PA).
- Last spring frost
- May 5
- First fall frost
- October 6
- Growing season
- 153 days
- Hardiness zone
- 6b
50% probability
50% probability
freeze-free, 50%
-5 to 0°F (-20.6 to -17.8°C) coldest night
- First snow
- November 28
- Last snow
- March 24
- Winters with snow
- 100%
- Snow per year
- 35.3"
median, 1991–2020
median, 1991–2020
26 of 26 observed
NOAA normal
Frost risk by date in Spring Mills
Half of springs at Millheim, PA see their last 32°F night by May 5; only one in ten is past it by April 22, and one in ten still has one after May 24. Planting tender crops after May 14 leaves a 30% risk of a frost on them, after May 19 20%, and after May 24 10%. The 19 days between the even-odds date and the one-in-ten date is wider than at 90% of the 176 Pennsylvania stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 6 in half of years, as early as September 25 one year in ten, and holds off past October 21 one year in ten. A hard freeze of 28°F follows 12 days later, around October 18; in spring the one-in-ten date for 28°F is May 13, 11 days before the 32°F one. The freeze-free season lasts 153 days in a typical year, shorter than at 85% of the 176 Pennsylvania stations; it reaches 175 days one year in ten and falls short of 132 one year in ten. On average 152 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 14 days longer, to about May 19, and return around September 27. Severe cold of 16°F or below comes every winter, usually between November 26 and March 21.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 1 | May 7 | May 11 | May 14 | May 19 | May 21 | May 25 | May 28 | May 31 |
| 32°F | Apr 22 | Apr 26 | Apr 29 | May 2 | May 5 | May 9 | May 14 | May 19 | May 24 |
| 28°F | Apr 11 | Apr 15 | Apr 18 | Apr 22 | Apr 24 | Apr 28 | May 1 | May 7 | May 13 |
| 24°F | Mar 29 | Apr 2 | Apr 5 | Apr 9 | Apr 12 | Apr 15 | Apr 17 | Apr 21 | Apr 27 |
| 20°F | Mar 16 | Mar 21 | Mar 25 | Mar 28 | Mar 31 | Apr 1 | Apr 5 | Apr 8 | Apr 13 |
| 16°F | Mar 5 | Mar 10 | Mar 15 | Mar 18 | Mar 21 | Mar 24 | Mar 27 | Mar 30 | Apr 2 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 14 | Sep 20 | Sep 22 | Sep 24 | Sep 27 | Sep 29 | Oct 1 | Oct 4 | Oct 8 |
| 32°F | Sep 25 | Sep 28 | Oct 1 | Oct 3 | Oct 6 | Oct 9 | Oct 12 | Oct 16 | Oct 21 |
| 28°F | Oct 4 | Oct 8 | Oct 12 | Oct 15 | Oct 18 | Oct 22 | Oct 25 | Oct 30 | Nov 3 |
| 24°F | Oct 14 | Oct 20 | Oct 25 | Oct 29 | Nov 1 | Nov 3 | Nov 6 | Nov 10 | Nov 14 |
| 20°F | Oct 29 | Nov 3 | Nov 6 | Nov 9 | Nov 13 | Nov 16 | Nov 20 | Nov 24 | Dec 1 |
| 16°F | Nov 9 | Nov 14 | Nov 18 | Nov 21 | Nov 26 | Nov 30 | Dec 3 | Dec 8 | Dec 15 |
Freeze probabilities 1991–2020 at Millheim, PA, 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 16875 →Compare Spring Mills with another place →
Weather by month in Spring Mills
July is the warmest month at Millheim, PA, averaging 84°F by day and 58°F at night; January is the coldest at 32°F and 15°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 63% of years.
Warmth for growing adds up to 2,568 growing degree days a year (base 50°F), fewer than at 74% of the 176 Pennsylvania stations. 34% of them (867) have built up by the end of June, and July adds the most, 656. Precipitation totals 42.4 inches a year, most in September (4.4") and least in February (2.3"); May to September bring 48% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 32 | 15 | 3.0 | 100% | 29 | 0 |
| Feb | 37 | 17 | 2.3 | 100% | 26 | 1 |
| Mar | 46 | 25 | 3.3 | 100% | 25 | 11 |
| Apr | 60 | 35 | 3.6 | 100% | 12 | 76 |
| May | 71 | 45 | 3.9 | 63% | 2 | 268 |
| Jun | 79 | 55 | 4.0 | 0% | 0 | 510 |
| Jul | 84 | 58 | 3.9 | 0% | 0 | 656 |
| Aug | 82 | 56 | 4.0 | 0% | 0 | 589 |
| Sep | 74 | 49 | 4.4 | 27% | 1 | 346 |
| Oct | 62 | 38 | 3.7 | 99% | 8 | 100 |
| Nov | 48 | 29 | 3.1 | 100% | 21 | 9 |
| Dec | 38 | 22 | 3.2 | 100% | 27 | 1 |
Monthly normals 1991–2020 at Millheim, PA (1,120 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, State College, PA, 16 miles west of Spring Mills, has a last frost 15 days earlier (April 20), a first frost 20 days later (October 26), a season 34 days longer.
When it snows in Spring Mills, Pennsylvania
The first measurable snow (0.1 inch or more) in Spring Mills usually arrives around November 28, and the last of the season around March 24. Those are the middle dates across the winters of 1991–2020 at Millheim, PA, 6.3 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 42 days after the last snow.
Planting calendar for 16875
| When | What to do |
|---|---|
| February 24 – March 10 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 10 – March 24 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 7 – April 21 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 5 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 14 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 22 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 6 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 16875 is 6 miles from Millheim, PA, which stands at 1,120 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station; its figures are presented in full for 16841 (Howard). The 2023 USDA Plant Hardiness Zone Map lists ZIP 16875 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°C) over 1991–2020; a zone describes winter lows, not frost dates.
Frost dates across Pennsylvania →
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.