USDA Hardiness Zone 7a
Frost Dates for 18901 — Doylestown, Pennsylvania
NOAA 1991–2020 normals from Doylestown Airport, PA (394 ft), under a mile north.
Updated
In Doylestown, the last spring frost (32°F) is around April 13 in half of years and has passed by April 27 in nine years out of ten. The first fall frost comes around October 30, as early as October 15 one year in ten, leaving a typical freeze-free season of 198 days (NOAA, Doylestown Airport, PA).
- Last spring frost
- April 13
- First fall frost
- October 30
- Growing season
- 198 days
- Hardiness zone
- 7a
50% probability
50% probability
freeze-free, 50%
0 to 5°F (-17.8 to -15.0°C) coldest night
- First snow
- December 26
- Last snow
- March 21
- Winters with snow
- 100%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
16 of 16 observed
NOAA normal
Frost risk by date in Doylestown
Half of springs at Doylestown Airport, PA see their last 32°F night by April 13; only one in ten is past it by April 1, and one in ten still has one after April 27. Planting tender crops after April 19 leaves a 30% risk of a frost on them, after April 22 20%, and after April 27 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 86% of the 176 Pennsylvania stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 30 in half of years, as early as October 15 one year in ten, and holds off past November 12 one year in ten. A hard freeze of 28°F follows 11 days later, around November 10; in spring the one-in-ten date for 28°F is April 14, 13 days before the 32°F one. The freeze-free season lasts 198 days in a typical year, longer than at 88% of the 176 Pennsylvania stations; it reaches 217 days one year in ten and falls short of 176 one year in ten. On average 106 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 April 27, and return around October 18. Severe cold of 16°F or below comes every winter, usually between December 22 and February 28.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 14 | Apr 18 | Apr 21 | Apr 24 | Apr 27 | Apr 30 | May 2 | May 6 | May 11 |
| 32°F | Apr 1 | Apr 4 | Apr 7 | Apr 11 | Apr 13 | Apr 16 | Apr 19 | Apr 22 | Apr 27 |
| 28°F | Mar 17 | Mar 23 | Mar 28 | Mar 31 | Apr 2 | Apr 3 | Apr 6 | Apr 9 | Apr 14 |
| 24°F | Mar 6 | Mar 11 | Mar 15 | Mar 18 | Mar 21 | Mar 25 | Mar 28 | Mar 31 | Apr 3 |
| 20°F | Feb 22 | Feb 28 | Mar 5 | Mar 8 | Mar 12 | Mar 15 | Mar 18 | Mar 21 | Mar 27 |
| 16°F | Feb 5 | Feb 13 | Feb 19 | Feb 24 | Feb 28 | Mar 4 | Mar 8 | Mar 13 | Mar 19 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 5 | Oct 9 | Oct 12 | Oct 15 | Oct 18 | Oct 21 | Oct 24 | Oct 28 | Nov 1 |
| 32°F | Oct 15 | Oct 20 | Oct 24 | Oct 27 | Oct 30 | Nov 1 | Nov 4 | Nov 8 | Nov 12 |
| 28°F | Oct 27 | Nov 1 | Nov 4 | Nov 7 | Nov 10 | Nov 12 | Nov 16 | Nov 19 | Nov 25 |
| 24°F | Nov 8 | Nov 13 | Nov 17 | Nov 20 | Nov 24 | Nov 27 | Nov 30 | Dec 3 | Dec 10 |
| 20°F | Nov 17 | Nov 23 | Nov 29 | Dec 2 | Dec 5 | Dec 8 | Dec 14 | Dec 20 | Dec 26 |
| 16°F | Dec 1 | Dec 7 | Dec 12 | Dec 18 | Dec 22 | Dec 25 | Dec 30 | Jan 4 | Jan 13 |
Freeze probabilities 1991–2020 at Doylestown Airport, 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 18901 →Compare Doylestown with another place →
Weather by month in Doylestown
July is the warmest month at Doylestown Airport, PA, averaging 86°F by day and 65°F at night; January is the coldest at 39°F and 23°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month.
Warmth for growing adds up to 3,410 growing degree days a year (base 50°F), more than at 86% of the 176 Pennsylvania stations. 33% of them (1,142) have built up by the end of June, and July adds the most, 786. Precipitation totals 48.0 inches a year, most in July (5.5") and least in February (2.5"); May to September bring 49% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 39 | 23 | 3.2 | 100% | 26 | 3 |
| Feb | 42 | 25 | 2.5 | 100% | 24 | 5 |
| Mar | 50 | 31 | 3.9 | 100% | 17 | 26 |
| Apr | 63 | 41 | 3.9 | 91% | 4 | 136 |
| May | 72 | 51 | 4.3 | 6% | 0 | 363 |
| Jun | 81 | 60 | 4.2 | 0% | 0 | 609 |
| Jul | 86 | 65 | 5.5 | 0% | 0 | 786 |
| Aug | 84 | 63 | 4.9 | 0% | 0 | 728 |
| Sep | 77 | 57 | 4.4 | 0% | 0 | 505 |
| Oct | 65 | 45 | 3.8 | 53% | 2 | 199 |
| Nov | 54 | 36 | 3.4 | 100% | 11 | 42 |
| Dec | 44 | 28 | 4.0 | 100% | 22 | 9 |
Monthly normals 1991–2020 at Doylestown Airport, PA (394 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, Willow Grove NAS, PA, 8 miles south of Doylestown, has a last frost 2 days earlier (April 11), a first frost 2 days later (November 1), a season 7 days longer.
When it snows in Doylestown, Pennsylvania
The first measurable snow (0.1 inch or more) in Doylestown usually arrives around December 26, and the last of the season around March 21. Those are the middle dates across the winters of 1991–2020 at Willow Grove NAS, PA, 8.2 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 23 days after the last snow.
Planting calendar for 18901
| When | What to do |
|---|---|
| February 2 – February 16 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 16 – March 2 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 16 – March 30 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 13 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 7 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 16 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 30 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 18901 is under a mile from Doylestown Airport, PA, which stands at 394 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 5 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 18901 in zone 7a, the band where the coldest night of the year averaged 0 to 5°F (-17.8 to -15.0°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.