USDA Hardiness Zone 6b
Frost Dates for 17844 — Mifflinburg, Pennsylvania
NOAA 1991–2020 normals from Laurelton Ctr, PA (800 ft), 9 miles west.
Updated
In Mifflinburg, the last spring frost (32°F) is around April 25 in half of years and has passed by May 11 in nine years out of ten. The first fall frost comes around October 19, as early as October 4 one year in ten, leaving a typical freeze-free season of 175 days (NOAA, Laurelton Ctr, PA).
- Last spring frost
- April 25
- First fall frost
- October 19
- Growing season
- 175 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
- December 17
- Last snow
- March 17
- Winters with snow
- 100%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
16 of 16 observed
NOAA normal
Frost risk by date in Mifflinburg
Half of springs at Laurelton Ctr, PA see their last 32°F night by April 25; only one in ten is past it by April 12, and one in ten still has one after May 11. Planting tender crops after May 1 leaves a 30% risk of a frost on them, after May 5 20%, and after May 11 10%. The 16 days between the even-odds date and the one-in-ten date is narrower than at 51% of the 176 Pennsylvania stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 19 in half of years, as early as October 4 one year in ten, and holds off past November 2 one year in ten. A hard freeze of 28°F follows 14 days later, around November 2; in spring the one-in-ten date for 28°F is April 28, 13 days before the 32°F one. The freeze-free season lasts 175 days in a typical year, shorter than at 48% of the 176 Pennsylvania stations; it reaches 196 days one year in ten and falls short of 157 one year in ten. On average 142 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 10 days longer, to about May 5, and return around October 7. Severe cold of 16°F or below comes every winter, usually between December 9 and March 11.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 23 | Apr 27 | Apr 30 | May 2 | May 5 | May 8 | May 12 | May 16 | May 21 |
| 32°F | Apr 12 | Apr 17 | Apr 20 | Apr 22 | Apr 25 | Apr 28 | May 1 | May 5 | May 11 |
| 28°F | Mar 31 | Apr 3 | Apr 7 | Apr 10 | Apr 12 | Apr 15 | Apr 18 | Apr 21 | Apr 28 |
| 24°F | Mar 17 | Mar 23 | Mar 27 | Mar 30 | Apr 1 | Apr 3 | Apr 5 | Apr 9 | Apr 14 |
| 20°F | Mar 5 | Mar 11 | Mar 14 | Mar 17 | Mar 20 | Mar 22 | Mar 26 | Mar 29 | Apr 1 |
| 16°F | Feb 22 | Feb 28 | Mar 4 | Mar 8 | Mar 11 | Mar 14 | Mar 17 | Mar 19 | Mar 24 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 25 | Sep 29 | Oct 1 | Oct 4 | Oct 7 | Oct 9 | Oct 12 | Oct 15 | Oct 21 |
| 32°F | Oct 4 | Oct 8 | Oct 12 | Oct 16 | Oct 19 | Oct 23 | Oct 26 | Oct 30 | Nov 2 |
| 28°F | Oct 16 | Oct 22 | Oct 27 | Oct 30 | Nov 2 | Nov 4 | Nov 6 | Nov 10 | Nov 16 |
| 24°F | Nov 1 | Nov 4 | Nov 7 | Nov 10 | Nov 13 | Nov 17 | Nov 20 | Nov 23 | Nov 28 |
| 20°F | Nov 9 | Nov 16 | Nov 20 | Nov 23 | Nov 26 | Nov 29 | Dec 2 | Dec 6 | Dec 14 |
| 16°F | Nov 22 | Nov 28 | Dec 2 | Dec 5 | Dec 9 | Dec 15 | Dec 20 | Dec 25 | Jan 1 |
Freeze probabilities 1991–2020 at Laurelton Ctr, 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 17844 →Compare Mifflinburg with another place →
Weather by month in Mifflinburg
July is the warmest month at Laurelton Ctr, PA, averaging 85°F by day and 62°F at night; January is the coldest at 36°F and 21°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 31% of years.
Warmth for growing adds up to 3,160 growing degree days a year (base 50°F), more than at 66% of the 176 Pennsylvania stations. 35% of them (1,096) have built up by the end of June, and July adds the most, 739.
| Month | High °F | Low °F | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|
| Jan | 36 | 21 | 100% | 29 | 2 |
| Feb | 41 | 22 | 100% | 25 | 1 |
| Mar | 50 | 28 | 100% | 24 | 16 |
| Apr | 64 | 38 | 99% | 11 | 123 |
| May | 75 | 49 | 31% | 2 | 369 |
| Jun | 81 | 58 | 0% | 0 | 585 |
| Jul | 85 | 62 | 0% | 0 | 739 |
| Aug | 84 | 61 | 0% | 0 | 688 |
| Sep | 76 | 54 | 4% | <1 | 448 |
| Oct | 65 | 42 | 84% | 7 | 159 |
| Nov | 52 | 33 | 100% | 17 | 26 |
| Dec | 40 | 26 | 100% | 27 | 3 |
Monthly normals 1991–2020 at Laurelton Ctr, PA (800 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, Lewisburg, PA, 9 miles east of Mifflinburg and 300 feet lower, has a last frost 1 day later (April 26), a first frost 1 day later (October 20), a season 1 day longer.
When it snows in Mifflinburg, Pennsylvania
The first measurable snow (0.1 inch or more) in Mifflinburg usually arrives around December 17, and the last of the season around March 17. Those are the middle dates across the winters of 1991–2020 at Laurelton Ctr, PA, 8.6 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 39 days after the last snow.
Planting calendar for 17844
| When | What to do |
|---|---|
| February 14 – February 28 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 28 – March 14 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 28 – April 11 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 25 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 27 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 5 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 19 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 17844 is 9 miles from Laurelton Ctr, PA, which stands at 800 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 17844 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.