USDA Hardiness Zone 7a
Frost Dates for 17584 — Willow Street, Pennsylvania
NOAA 1991–2020 normals from Lancaster 2NE Fltr Plt, PA (270 ft), 6 miles north.
Updated
In Willow Street, the last spring frost (32°F) is around April 19 in half of years and has passed by May 7 in nine years out of ten. The first fall frost comes around October 24, as early as October 9 one year in ten, leaving a typical freeze-free season of 186 days (NOAA, Lancaster 2NE Fltr Plt, PA).
- Last spring frost
- April 19
- First fall frost
- October 24
- Growing season
- 186 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 17
- Last snow
- March 8
- Winters with snow
- 97%
- Snow per year
- 21.4"
median, 1991–2020
median, 1991–2020
29 of 30 observed
NOAA normal
Frost risk by date in Willow Street
Half of springs at Lancaster 2NE Fltr Plt, PA see their last 32°F night by April 19; only one in ten is past it by April 5, and one in ten still has one after May 7. Planting tender crops after April 27 leaves a 30% risk of a frost on them, after May 2 20%, and after May 7 10%. The 18 days between the even-odds date and the one-in-ten date is wider than at 70% of the 176 Pennsylvania stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 24 in half of years, as early as October 9 one year in ten, and holds off past November 6 one year in ten. A hard freeze of 28°F follows 11 days later, around November 4; in spring the one-in-ten date for 28°F is April 24, 13 days before the 32°F one. The freeze-free season lasts 186 days in a typical year, longer than at 72% of the 176 Pennsylvania stations; it reaches 205 days one year in ten and falls short of 163 one year in ten. On average 111 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 13 days longer, to about May 2, and return around October 13. Severe cold of 16°F or below comes every winter, usually between December 20 and March 2.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 19 | Apr 23 | Apr 26 | Apr 30 | May 2 | May 5 | May 9 | May 14 | May 20 |
| 32°F | Apr 5 | Apr 10 | Apr 14 | Apr 17 | Apr 19 | Apr 22 | Apr 27 | May 2 | May 7 |
| 28°F | Mar 22 | Mar 28 | Mar 31 | Apr 2 | Apr 5 | Apr 8 | Apr 12 | Apr 17 | Apr 24 |
| 24°F | Mar 8 | Mar 13 | Mar 17 | Mar 21 | Mar 24 | Mar 27 | Mar 30 | Apr 1 | Apr 5 |
| 20°F | Feb 25 | Mar 2 | Mar 5 | Mar 9 | Mar 12 | Mar 15 | Mar 18 | Mar 22 | Mar 26 |
| 16°F | Feb 10 | Feb 16 | Feb 22 | Feb 27 | Mar 2 | Mar 5 | Mar 9 | Mar 13 | Mar 18 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 2 | Oct 5 | Oct 8 | Oct 11 | Oct 13 | Oct 16 | Oct 19 | Oct 22 | Oct 27 |
| 32°F | Oct 9 | Oct 15 | Oct 17 | Oct 21 | Oct 24 | Oct 27 | Oct 30 | Nov 2 | Nov 6 |
| 28°F | Oct 20 | Oct 26 | Oct 30 | Nov 1 | Nov 4 | Nov 6 | Nov 10 | Nov 14 | Nov 20 |
| 24°F | Nov 3 | Nov 8 | Nov 12 | Nov 15 | Nov 18 | Nov 21 | Nov 25 | Nov 30 | Dec 5 |
| 20°F | Nov 16 | Nov 20 | Nov 25 | Nov 29 | Dec 2 | Dec 6 | Dec 10 | Dec 15 | Dec 23 |
| 16°F | Nov 29 | Dec 5 | Dec 10 | Dec 14 | Dec 20 | Dec 24 | Dec 28 | Jan 1 | Jan 9 |
Freeze probabilities 1991–2020 at Lancaster 2NE Fltr Plt, 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 17584 →Compare Willow Street with another place →
Weather by month in Willow Street
July is the warmest month at Lancaster 2NE Fltr Plt, PA, averaging 87°F by day and 65°F at night; January is the coldest at 40°F and 22°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 23% of years.
Warmth for growing adds up to 3,496 growing degree days a year (base 50°F), more than at 89% of the 176 Pennsylvania stations. 34% of them (1,202) have built up by the end of June, and July adds the most, 801. Precipitation totals 44.2 inches a year, most in September (4.8") and least in February (2.5"); May to September bring 47% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 40 | 22 | 3.0 | 100% | 26 | 3 |
| Feb | 43 | 24 | 2.5 | 100% | 23 | 4 |
| Mar | 52 | 31 | 3.5 | 100% | 18 | 28 |
| Apr | 65 | 41 | 3.5 | 95% | 4 | 143 |
| May | 75 | 50 | 3.7 | 23% | <1 | 389 |
| Jun | 83 | 60 | 4.1 | 0% | 0 | 636 |
| Jul | 87 | 65 | 4.5 | 0% | 0 | 801 |
| Aug | 85 | 63 | 3.6 | 0% | 0 | 746 |
| Sep | 78 | 56 | 4.8 | 0% | 0 | 508 |
| Oct | 66 | 44 | 4.2 | 74% | 2 | 193 |
| Nov | 55 | 34 | 3.3 | 100% | 13 | 39 |
| Dec | 44 | 27 | 3.5 | 100% | 24 | 7 |
Monthly normals 1991–2020 at Lancaster 2NE Fltr Plt, PA (270 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, Safe Harbor Dam, PA, 7 miles southwest of Willow Street, has a last frost 18 days earlier (April 1), a first frost 17 days later (November 10), a season 35 days longer.
When it snows in Willow Street, Pennsylvania
The first measurable snow (0.1 inch or more) in Willow Street usually arrives around December 17, and the last of the season around March 8. Those are the middle dates across the winters of 1991–2020 at Lancaster 2NE Fltr Plt, PA, 6 miles away: half of years saw snow earlier, half later. Snow fell in 97% of those winters. The last 32°F night of spring typically comes 42 days after the last snow.
Planting calendar for 17584
| When | What to do |
|---|---|
| February 8 – February 22 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 22 – March 8 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 22 – April 5 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 19 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 1 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 10 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 24 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 17584 is 6 miles from Lancaster 2NE Fltr Plt, PA, which stands at 270 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 6 other ZIP codes share the station; its figures are presented in full for 17603 (Lancaster). The 2023 USDA Plant Hardiness Zone Map lists ZIP 17584 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.