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USDA Hardiness Zone 6b

Frost Dates for 15132 — Mckeesport, Pennsylvania

NOAA 1991–2020 normals from Mckeesport, PA (740 ft), under a mile west.

Updated

In Mckeesport, the last spring frost (32°F) is around May 2 in half of years and has passed by May 20 in nine years out of ten. The first fall frost comes around October 20, as early as October 1 one year in ten, leaving a typical freeze-free season of 170 days (NOAA, Mckeesport, PA).

Last spring frost
May 2

50% probability

First fall frost
October 20

50% probability

Growing season
170 days

freeze-free, 50%

Hardiness zone
6b

-5 to 0°F (-20.6 to -17.8°C) coldest night

First snow
December 22

median, 1991–2020

Last snow
February 22

median, 1991–2020

Winters with snow
81%

21 of 26 observed

Snow per year
—

NOAA normal

Frost risk by date in Mckeesport

Half of springs at Mckeesport, PA see their last 32°F night by May 2; only one in ten is past it by April 17, and one in ten still has one after May 20. Planting tender crops after May 10 leaves a 30% risk of a frost on them, after May 14 20%, and after May 20 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 20 in half of years, as early as October 1 one year in ten, and holds off past November 3 one year in ten. A hard freeze of 28°F follows 12 days later, around November 1; in spring the one-in-ten date for 28°F is May 10, 10 days before the 32°F one. The freeze-free season lasts 170 days in a typical year, shorter than at 60% of the 176 Pennsylvania stations; it reaches 192 days one year in ten and falls short of 144 one year in ten. On average 124 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 12, and return around October 7. Severe cold of 16°F or below comes every winter, usually between December 10 and March 10.

Spring: the chance of another night this cold after the date
Low90%80%70%60%50%40%30%20%10%
36°FApr 26Apr 30May 4May 8May 12May 15May 19May 23May 27
32°FApr 17Apr 22Apr 26Apr 29May 2May 5May 10May 14May 20
28°FApr 2Apr 7Apr 13Apr 16Apr 20Apr 24Apr 29May 4May 10
24°FMar 18Mar 24Mar 29Apr 1Apr 4Apr 7Apr 13Apr 19Apr 30
20°FMar 4Mar 11Mar 15Mar 18Mar 22Mar 27Mar 31Apr 3Apr 10
16°FFeb 19Feb 28Mar 3Mar 7Mar 10Mar 15Mar 18Mar 22Mar 30
Fall: the chance the first night this cold has come by the date
Low10%20%30%40%50%60%70%80%90%
36°FSep 21Sep 28Oct 2Oct 5Oct 7Oct 11Oct 14Oct 17Oct 24
32°FOct 1Oct 6Oct 11Oct 15Oct 20Oct 24Oct 27Oct 31Nov 3
28°FOct 10Oct 20Oct 25Oct 30Nov 1Nov 3Nov 6Nov 10Nov 14
24°FOct 28Nov 2Nov 5Nov 9Nov 12Nov 15Nov 18Nov 23Dec 1
20°FNov 8Nov 13Nov 18Nov 22Nov 26Nov 30Dec 3Dec 7Dec 16
16°FNov 18Nov 26Dec 1Dec 5Dec 10Dec 15Dec 20Dec 25Jan 1

Freeze probabilities 1991–2020 at Mckeesport, 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 15132 →Compare Mckeesport with another place →

Weather by month in Mckeesport

July is the warmest month at Mckeesport, PA, averaging 85°F by day and 61°F at night; January is the coldest at 39°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 54% of years.

Warmth for growing adds up to 3,104 growing degree days a year (base 50°F), more than at 60% of the 176 Pennsylvania stations. 34% of them (1,066) have built up by the end of June, and July adds the most, 714. Precipitation totals 42.4 inches a year, most in June (5.0") and least in February (2.5"); May to September bring 47% of it.

Monthly normals 1991–2020 at Mckeesport, PA
MonthHigh °FLow °FPrecip. in32°F nightNights ≤ 32°FGDD 50°F
Jan39213.0100%264
Feb42222.5100%245
Mar51293.2100%2030
Apr64383.899%8125
May74474.054%1336
Jun81575.00%0567
Jul85614.10%0714
Aug83603.50%0674
Sep77533.510%<1449
Oct65423.278%4162
Nov53323.0100%1731
Dec43253.6100%247

Monthly normals 1991–2020 at Mckeesport, PA (740 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, Braddock Lock 2, PA, 3 miles north of Mckeesport, has a last frost 27 days earlier (April 5), a first frost 21 days later (November 10), a season 49 days longer.

Frost dates for 15235 (Pittsburgh) →

When it snows in Mckeesport, Pennsylvania

The first measurable snow (0.1 inch or more) in Mckeesport usually arrives around December 22, and the last of the season around February 22. Those are the middle dates across the winters of 1991–2020 at Braddock Lock 2, PA, 3.5 miles away: half of years saw snow earlier, half later. Snow fell in 81% of those winters. The last 32°F night of spring typically comes 69 days after the last snow.

Planting calendar for 15132

What to do and when, from the 50% frost dates for Mckeesport, Pennsylvania
WhenWhat to do
February 21 – March 7Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out.
March 7 – March 21Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early.
April 4 – April 18Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil.
May 2 onwardTransplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast.
by July 28Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops.
by October 6Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation.
October 20 onwardPlant 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 15132 is under a mile from Mckeesport, PA, which stands at 740 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 6 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 15132 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.

ZIP codes measured at the same station

Other zone 6b places in Pennsylvania