USDA Hardiness Zone 6b
Frost Dates for 15636 — Harrison City, Pennsylvania
NOAA 1991–2020 normals from Murrysville 2 SW, PA (860 ft), 5 miles northwest.
Updated
In Harrison City, the last spring frost (32°F) is around April 22 in half of years and has passed by May 12 in nine years out of ten. The first fall frost comes around October 25, as early as October 10 one year in ten, leaving a typical freeze-free season of 186 days (NOAA, Murrysville 2 SW, PA).
- Last spring frost
- April 22
- First fall frost
- October 25
- Growing season
- 186 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 12
- Last snow
- March 12
- Winters with snow
- 100%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
16 of 16 observed
NOAA normal
Frost risk by date in Harrison City
Half of springs at Murrysville 2 SW, PA see their last 32°F night by April 22; only one in ten is past it by April 7, and one in ten still has one after May 12. Planting tender crops after April 29 leaves a 30% risk of a frost on them, after May 5 20%, and after May 12 10%. The 20 days between the even-odds date and the one-in-ten date is wider than at 98% of the 176 Pennsylvania stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 25 in half of years, as early as October 10 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 5; in spring the one-in-ten date for 28°F is April 23, 19 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 207 days one year in ten and falls short of 163 one year in ten. On average 129 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 5, and return around October 13. Severe cold of 16°F or below comes every winter, usually between December 12 and March 8.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 19 | Apr 23 | Apr 28 | May 1 | May 5 | May 8 | May 12 | May 16 | May 20 |
| 32°F | Apr 7 | Apr 12 | Apr 17 | Apr 20 | Apr 22 | Apr 25 | Apr 29 | May 5 | May 12 |
| 28°F | Mar 24 | Mar 31 | Apr 2 | Apr 5 | Apr 7 | Apr 11 | Apr 15 | Apr 18 | Apr 23 |
| 24°F | Mar 13 | Mar 18 | Mar 21 | Mar 25 | Mar 28 | Mar 31 | Apr 2 | Apr 5 | Apr 10 |
| 20°F | Feb 28 | Mar 6 | Mar 11 | Mar 14 | Mar 17 | Mar 19 | Mar 23 | Mar 27 | Mar 31 |
| 16°F | Feb 14 | Feb 23 | Feb 28 | Mar 4 | Mar 8 | Mar 11 | Mar 15 | Mar 18 | Mar 23 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 1 | Oct 5 | Oct 8 | Oct 10 | Oct 13 | Oct 16 | Oct 19 | Oct 22 | Oct 26 |
| 32°F | Oct 10 | Oct 15 | Oct 19 | Oct 22 | Oct 25 | Oct 28 | Oct 30 | Nov 2 | Nov 6 |
| 28°F | Oct 23 | Oct 28 | Oct 31 | Nov 2 | Nov 5 | Nov 8 | Nov 11 | Nov 15 | Nov 20 |
| 24°F | Nov 3 | Nov 7 | Nov 11 | Nov 14 | Nov 17 | Nov 20 | Nov 24 | Nov 28 | Dec 3 |
| 20°F | Nov 11 | Nov 16 | Nov 21 | Nov 25 | Nov 28 | Dec 1 | Dec 6 | Dec 11 | Dec 20 |
| 16°F | Nov 21 | Nov 28 | Dec 2 | Dec 7 | Dec 12 | Dec 17 | Dec 23 | Dec 29 | Jan 4 |
Freeze probabilities 1991–2020 at Murrysville 2 SW, 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 15636 →Compare Harrison City with another place →
Compared with the next station
The nearest other station, Mckeesport, PA, 11 miles west of Harrison City, has a last frost 10 days later (May 2), a first frost 5 days earlier (October 20), a season 16 days shorter.
When it snows in Harrison City, Pennsylvania
The first measurable snow (0.1 inch or more) in Harrison City usually arrives around December 12, and the last of the season around March 12. Those are the middle dates across the winters of 1991–2020 at New Stanton 1 SW, PA, 10.9 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 41 days after the last snow.
Planting calendar for 15636
| When | What to do |
|---|---|
| February 11 – February 25 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 25 – March 11 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 25 – April 8 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 22 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 2 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 11 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 25 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 15636 is 5 miles from Murrysville 2 SW, PA, which stands at 860 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 8 other ZIP codes share the station; its figures are presented in full for 15642 (Irwin). The 2023 USDA Plant Hardiness Zone Map lists ZIP 15636 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.