USDA Hardiness Zone 6b
Frost Dates for 15218 — Pittsburgh, Pennsylvania
NOAA 1991–2020 normals from Braddock Lock 2, PA (730 ft), 3 miles southeast.
Updated
In Pittsburgh, the last spring frost (32°F) is around April 5 in half of years and has passed by April 22 in nine years out of ten. The first fall frost comes around November 10, as early as October 28 one year in ten, leaving a typical freeze-free season of 219 days (NOAA, Braddock Lock 2, PA).
- Last spring frost
- April 5
- First fall frost
- November 10
- Growing season
- 219 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 22
- Last snow
- February 22
- Winters with snow
- 81%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
21 of 26 observed
NOAA normal
Frost risk by date in Pittsburgh
Half of springs at Braddock Lock 2, PA see their last 32°F night by April 5; only one in ten is past it by March 22, and one in ten still has one after April 22. Planting tender crops after April 12 leaves a 30% risk of a frost on them, after April 16 20%, and after April 22 10%. The 17 days between the even-odds date and the one-in-ten date is wider than at 50% of the 176 Pennsylvania stations behind this site's ZIP pages.
In fall the first 32°F night comes by November 10 in half of years, as early as October 28 one year in ten, and holds off past November 27 one year in ten. A hard freeze of 28°F follows 13 days later, around November 23; in spring the one-in-ten date for 28°F is April 9, 13 days before the 32°F one. The freeze-free season lasts 219 days in a typical year, longer than at 98% of the 176 Pennsylvania stations; it reaches 240 days one year in ten and falls short of 196 one year in ten. On average 92 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 15 days longer, to about April 20, and return around October 29. Severe cold of 16°F or below comes every winter, usually between December 29 and February 26.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 3 | Apr 8 | Apr 12 | Apr 16 | Apr 20 | Apr 23 | Apr 27 | May 2 | May 11 |
| 32°F | Mar 22 | Mar 27 | Mar 31 | Apr 2 | Apr 5 | Apr 8 | Apr 12 | Apr 16 | Apr 22 |
| 28°F | Mar 12 | Mar 17 | Mar 20 | Mar 23 | Mar 27 | Mar 29 | Mar 31 | Apr 3 | Apr 9 |
| 24°F | Feb 28 | Mar 5 | Mar 9 | Mar 12 | Mar 16 | Mar 18 | Mar 22 | Mar 26 | Mar 30 |
| 20°F | Feb 14 | Feb 23 | Feb 28 | Mar 3 | Mar 7 | Mar 10 | Mar 14 | Mar 17 | Mar 22 |
| 16°F | Jan 31 | Feb 6 | Feb 13 | Feb 19 | Feb 26 | Mar 1 | Mar 5 | Mar 9 | Mar 16 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 13 | Oct 19 | Oct 23 | Oct 26 | Oct 29 | Nov 1 | Nov 3 | Nov 6 | Nov 12 |
| 32°F | Oct 28 | Nov 1 | Nov 4 | Nov 6 | Nov 10 | Nov 12 | Nov 16 | Nov 21 | Nov 27 |
| 28°F | Nov 6 | Nov 11 | Nov 15 | Nov 19 | Nov 23 | Nov 26 | Nov 30 | Dec 4 | Dec 10 |
| 24°F | Nov 14 | Nov 21 | Nov 26 | Dec 1 | Dec 3 | Dec 8 | Dec 13 | Dec 17 | Dec 23 |
| 20°F | Nov 27 | Dec 4 | Dec 9 | Dec 13 | Dec 18 | Dec 22 | Dec 26 | Dec 31 | Jan 7 |
| 16°F | Dec 10 | Dec 15 | Dec 21 | Dec 25 | Dec 29 | Jan 1 | Jan 6 | Jan 11 | Jan 18 |
Freeze probabilities 1991–2020 at Braddock Lock 2, 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 15218 →Compare Pittsburgh with another place →
Compared with the next station
The nearest other station, Pittsburgh Allegheny Co Airport, PA, 5 miles south of Pittsburgh and 518 feet higher, has a last frost 13 days later (April 18), a first frost 13 days earlier (October 28), a season 26 days shorter.
When it snows in Pittsburgh, Pennsylvania
The first measurable snow (0.1 inch or more) in Pittsburgh 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, 2.7 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 42 days after the last snow.
Planting calendar for 15218
| When | What to do |
|---|---|
| January 25 – February 8 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 8 – February 22 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 8 – March 22 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 5 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 18 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 27 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| November 10 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 15218 is 3 miles from Braddock Lock 2, PA, which stands at 730 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 16 other ZIP codes share the station; its figures are presented in full for 15235 (Pittsburgh). The 2023 USDA Plant Hardiness Zone Map lists ZIP 15218 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.