Checking current alerts… View NWS forecast and alerts.
Will it freeze in West Mifflin in the next 7 nights?
No overnight lows at or below 32°F are forecast in West Mifflin during the next 7 nights in the available NWS frost forecast.
Tonight: forecast low 49°F. Above 36°F.
NWS forecast period: Thu, Nov 5, 6:00 PM EST to Fri, Nov 6, 6:00 AM EST.
No nights at or below 36°F in the National Weather Service forecast for the next 7 nights.
- Tonight 49°F Above 36°F · Partly Cloudy
- Fri, Nov 6 41°F Above 36°F · Chance Light Rain
- Sat, Nov 7 40°F Above 36°F · Chance Light Rain then Mostly Cloudy
- Sun, Nov 8 37°F Above 36°F · Mostly Clear
- Mon, Nov 9 40°F Above 36°F · Mostly Clear
- Tue, Nov 10 38°F Above 36°F · Mostly Clear
- Wed, Nov 11 37°F Above 36°F · Partly Cloudy
Overnight lows from the National Weather Service forecast for this location. This covers the available forecast window, not the first freeze of the whole season. Frost can form above 32°F on clear, calm nights.
Frost and freeze probabilities
Freeze dates shift from year to year. Spring percentages describe the chance of a freeze after the stated date; fall percentages describe the chance of a freeze by that date. The 10% spring date is the cautious one: a later freeze happens about 1 year in 10.
These dates describe historical probabilities, not this year’s forecast or the earliest and latest possible freezes. Different weather stations or probability thresholds can produce different published dates for the same city.
Average first hard freeze in West Mifflin
The median first fall hard-freeze date (28°F) is November 8, from NOAA’s 1991–2020 Climate Normals at Pittsburgh Allegheny County Airport. This is the 50% probability date, not a forecast for this year.
| Temperature | Last spring date 90% · 50% · 10% chance of a later freeze | First fall date 10% · 50% · 90% chance of an earlier freeze | Season |
|---|---|---|---|
| 36°F frost possible | Apr 16 · Apr 29 · May 17 | Oct 4 · Oct 17 · Oct 29 | 169 days |
| 32°F freeze | Apr 2 · Apr 18 · May 6 | Oct 14 · Oct 28 · Nov 10 | 193 days |
| 28°F hard freeze | Mar 23 · Apr 5 · Apr 21 | Oct 28 · Nov 8 · Nov 22 | 216 days |
Average high temperature by month
1991–2020 normals at Pittsburgh Allegheny County Airport
Average low temperature by month
Months with lows near or below freezing carry frost risk
Where these frost dates come from
The frost dates for West Mifflin, PA come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Pittsburgh Allegheny County Airport (station USW00014762, elevation 1,248 ft), 0.9 mi from West Mifflin. Local conditions (valleys, hilltops, distance to water, city heat) can shift frost dates by days or weeks. The hardiness zone is from the 2023 USDA Plant Hardiness Zone Map (USDA ARS and Oregon State University PRISM). See our methodology.
Frost dates near West Mifflin
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Munhall, PA | 2.5 mi | Apr 5 | Nov 10 |
| Baldwin, PA | 2.5 mi | Apr 18 | Oct 28 |
| Duquesne, PA | 3.1 mi | Apr 5 | Nov 10 |
| McKeesport, PA | 3.1 mi | May 2 | Oct 20 |
| Pleasant Hills, PA | 3.7 mi | Apr 18 | Oct 28 |
| Brentwood, PA | 3.7 mi | Apr 18 | Oct 28 |
| Clairton, PA | 4.3 mi | May 2 | Oct 20 |
| Swissvale, PA | 4.3 mi | Apr 5 | Nov 10 |
| Whitehall, PA | 4.3 mi | Apr 18 | Oct 28 |
| Jefferson Hills, PA | 4.3 mi | Apr 18 | Oct 28 |
Frequently asked questions
When is the last frost in West Mifflin?
On average, the last spring frost (32°F) in West Mifflin is around April 18. In about 1 year in 10 it comes after May 6, and in 9 years in 10 it comes after April 2.
When is the first frost in West Mifflin?
The first fall frost (32°F) usually arrives around October 28. There’s a 10% chance of a freeze by October 14 and a 90% chance by November 10.
Can it frost in West Mifflin after the last frost date?
Yes. Frost can form on clear, calm nights even when the air stays above 32°F. Temperatures of 36°F or lower, cold enough for frost on exposed plants, have a 50% chance of occurring after April 29.
What growing zone is West Mifflin?
West Mifflin is in USDA Plant Hardiness Zone 6b (average annual extreme minimum temperature −5 to 0°F), based on the 2023 USDA map for ZIP code 15122. See growing zones in Pennsylvania.
More: all Pennsylvania frost dates · Pennsylvania growing zones · frost vs. freeze