Frost dates for 15122 — West Mifflin, PA
Last spring frostMay 2median date
First fall frostOct 20median date
Growing season171 daysfrost-free
Hardiness zone6bZone 6b
How West Mifflin compares
- In 8 years out of 10, the last spring frost in West Mifflin falls between April 17 and May 20, a 33-day window. The first fall frost falls between October 1 and November 3.
- The median last frost is 5 days later than the Pennsylvania median of Apr 27.
- Its 171-day growing season is longer than 38% of the 1,787 Pennsylvania places with a regular frost season (state median 175 days).
- The last frost is 10 days later than the zone 6b median of Apr 22. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 6b chart.
- The weather station records an average of 124 nights a year at or below 32°F.
- Compared with Pittsburgh, PA, 15 km away, the last frost here is 8 days later than there and the growing season is 15 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 17 |
| 50% (median) | May 2 |
| 10% (safe for tender plants) | May 20 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 1 |
| 50% (median) | October 20 |
| 90% (late) | November 3 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for West Mifflin, PA
Frost dates for 15122 — West Mifflin, PA — last frost May 2, first frost Oct 20, zone 6b. whenisthelastfrost.com
Crop
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Start indoors: Feb 7 to Feb 21Transplant outside: Apr 4 to Apr 18
Start indoors: Feb 21 to Mar 7Transplant outside: May 16 to May 30
Start indoors: Feb 21 to Mar 7Transplant outside: May 16 to May 30
Start indoors: Mar 7 to Mar 21Transplant outside: May 9 to May 23
Start indoors: Mar 7 to Mar 21Transplant outside: Apr 11 to Apr 25Sow outdoors: Apr 4 to May 9Plant for fall: Aug 25 to Sep 22
Start indoors: Mar 7 to Mar 21Transplant outside: Apr 4 to Apr 18Sow outdoors: Apr 4 to Apr 18Plant for fall: Aug 11 to Sep 1
Start indoors: Mar 7 to Mar 21Transplant outside: Apr 18 to May 2Plant for fall: Jul 14 to Aug 4
Start indoors: Mar 7 to Mar 21Transplant outside: Apr 11 to Apr 25Plant for fall: Jul 14 to Aug 4
Start indoors: Mar 7 to Mar 21Transplant outside: Apr 18 to May 2Plant for fall: Jul 14 to Aug 4
Start indoors: Mar 21 to Apr 4Transplant outside: May 23 to Jun 6Sow outdoors: May 23 to Jun 6
Start indoors: Mar 21 to Apr 4Transplant outside: May 9 to May 23
Sow outdoors: Mar 21 to Apr 11Plant for fall: Jul 28 to Aug 18
Sow outdoors: Mar 21 to Apr 11Plant for fall: Aug 25 to Sep 15
Sow outdoors: Mar 28 to May 9Plant for fall: Sep 8 to Sep 29
Start indoors: Apr 4 to Apr 11Transplant outside: May 16 to May 23Sow outdoors: May 9 to May 23Plant for fall: Aug 4 to Aug 18
Start indoors: Apr 4 to Apr 11Sow outdoors: May 9 to May 23Plant for fall: Aug 11 to Aug 25
Start indoors: Apr 4 to Apr 11Sow outdoors: May 9 to May 23
Start indoors: Apr 4 to Apr 11Transplant outside: May 16 to May 30
Sow outdoors: Apr 11 to May 9Plant for fall: Jul 28 to Aug 11
Sow outdoors: Apr 11 to May 9Plant for fall: Aug 11 to Aug 25
Sow outdoors: Apr 11 to May 2
Sow outdoors: Apr 18 to May 16Plant for fall: Aug 11 to Aug 25
Sow outdoors: Apr 18 to May 9Plant for fall: Aug 25 to Sep 15
Sow outdoors: May 9 to May 30Plant for fall: Aug 4 to Aug 18
Sow outdoors: May 9 to May 23
Transplant outside: May 16 to Jun 6
Plant for fall: Oct 6 to Nov 10
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in West Mifflin, PA
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 7 – Feb 21 | Apr 4 – Apr 18 | — | — |
| Peppers | Feb 21 – Mar 7 | May 16 – May 30 | — | — |
| Eggplant | Feb 21 – Mar 7 | May 16 – May 30 | — | — |
| Tomatoes | Mar 7 – Mar 21 | May 9 – May 23 | — | — |
| Lettuce | Mar 7 – Mar 21 | Apr 11 – Apr 25 | Apr 4 – May 9 | Aug 25 – Sep 22 |
| Kale | Mar 7 – Mar 21 | Apr 4 – Apr 18 | Apr 4 – Apr 18 | Aug 11 – Sep 1 |
| Broccoli | Mar 7 – Mar 21 | Apr 18 – May 2 | — | Jul 14 – Aug 4 |
| Cabbage | Mar 7 – Mar 21 | Apr 11 – Apr 25 | — | Jul 14 – Aug 4 |
| Cauliflower | Mar 7 – Mar 21 | Apr 18 – May 2 | — | Jul 14 – Aug 4 |
| Okra | Mar 21 – Apr 4 | May 23 – Jun 6 | May 23 – Jun 6 | — |
| Basil | Mar 21 – Apr 4 | May 9 – May 23 | — | — |
| Peas | — | — | Mar 21 – Apr 11 | Jul 28 – Aug 18 |
| Spinach | — | — | Mar 21 – Apr 11 | Aug 25 – Sep 15 |
| Radishes | — | — | Mar 28 – May 9 | Sep 8 – Sep 29 |
| Cucumbers | Apr 4 – Apr 11 | May 16 – May 23 | May 9 – May 23 | Aug 4 – Aug 18 |
| Zucchini & Summer Squash | Apr 4 – Apr 11 | — | May 9 – May 23 | Aug 11 – Aug 25 |
| Winter Squash & Pumpkins | Apr 4 – Apr 11 | — | May 9 – May 23 | — |
| Melons & Watermelon | Apr 4 – Apr 11 | May 16 – May 30 | — | — |
| Carrots | — | — | Apr 11 – May 9 | Jul 28 – Aug 11 |
| Beets | — | — | Apr 11 – May 9 | Aug 11 – Aug 25 |
| Potatoes | — | — | Apr 11 – May 2 | — |
| Swiss Chard | — | — | Apr 18 – May 16 | Aug 11 – Aug 25 |
| Cilantro | — | — | Apr 18 – May 9 | Aug 25 – Sep 15 |
| Green Beans | — | — | May 9 – May 30 | Aug 4 – Aug 18 |
| Sweet Corn | — | — | May 9 – May 23 | — |
| Sweet Potatoes | — | May 16 – Jun 6 | — | — |
| Garlic | — | — | — | Oct 6 – Nov 10 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Mckeesport, PA weather station, 3 km away (elevation 741 ft (226 m)).
ZIP codes in West Mifflin: 15122 15123
Frost dates near West Mifflin
- Duquesne Apr 5 · Nov 10
- Mckeesport May 2 · Oct 20
- Dravosburg Apr 18 · Oct 28
- Glassport May 2 · Oct 20
- Braddock Apr 5 · Nov 10
- Homestead Apr 5 · Nov 10
- North Versailles Apr 5 · Nov 10
- East Pittsburgh Apr 5 · Nov 10
Frequently asked questions
When is the last frost in West Mifflin, PA?
The median last spring frost in West Mifflin, PA is May 2. There is still about a 10% chance of frost after May 20, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in West Mifflin, PA?
The median first fall frost is October 20, with about a 10% chance of frost before October 1.
How long is the growing season in West Mifflin, PA?
About 171 days between the median last spring frost and first fall frost.
What planting zone is West Mifflin, PA?
West Mifflin, PA is in USDA hardiness zone 6b.