USDA Hardiness Zone 6b
Frost Dates for 15003 — Ambridge, Pennsylvania
NOAA 1991–2020 normals from Glenwillard Dashields L&D, PA (710 ft), 3 miles south.
Updated
In Ambridge, the last spring frost (32°F) is around April 8 in half of years and has passed by April 26 in nine years out of ten. The first fall frost comes around November 8, as early as October 27 one year in ten, leaving a typical freeze-free season of 212 days (NOAA, Glenwillard Dashields L&D, PA).
- Last spring frost
- April 8
- First fall frost
- November 8
- Growing season
- 212 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 24
- Last snow
- February 23
- Winters with snow
- 88%
- Snow per year
- 19.8"
median, 1991–2020
median, 1991–2020
23 of 26 observed
NOAA normal
Frost risk by date in Ambridge
Half of springs at Glenwillard Dashields L&D, PA see their last 32°F night by April 8; only one in ten is past it by March 25, and one in ten still has one after April 26. Planting tender crops after April 16 leaves a 30% risk of a frost on them, after April 20 20%, and after April 26 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 November 8 in half of years, as early as October 27 one year in ten, and holds off past November 24 one year in ten. A hard freeze of 28°F follows 10 days later, around November 18; in spring the one-in-ten date for 28°F is April 12, 14 days before the 32°F one. The freeze-free season lasts 212 days in a typical year, longer than at 96% of the 176 Pennsylvania stations; it reaches 233 days one year in ten and falls short of 190 one year in ten. On average 93 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 16 days longer, to about April 24, and return around October 28. Severe cold of 16°F or below comes every winter, usually between December 26 and February 28.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 7 | Apr 13 | Apr 17 | Apr 21 | Apr 24 | Apr 28 | May 2 | May 7 | May 13 |
| 32°F | Mar 25 | Mar 30 | Apr 2 | Apr 5 | Apr 8 | Apr 12 | Apr 16 | Apr 20 | Apr 26 |
| 28°F | Mar 14 | Mar 19 | Mar 23 | Mar 27 | Mar 29 | Mar 31 | Apr 3 | Apr 6 | Apr 12 |
| 24°F | Mar 2 | Mar 8 | Mar 13 | Mar 16 | Mar 19 | Mar 22 | Mar 25 | Mar 28 | Mar 31 |
| 20°F | Feb 16 | Feb 25 | Mar 1 | Mar 5 | Mar 9 | Mar 12 | Mar 16 | Mar 20 | Mar 25 |
| 16°F | Feb 2 | Feb 11 | Feb 19 | Feb 24 | Feb 28 | Mar 4 | Mar 8 | Mar 12 | Mar 17 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 13 | Oct 18 | Oct 22 | Oct 25 | Oct 28 | Oct 31 | Nov 2 | Nov 5 | Nov 10 |
| 32°F | Oct 27 | Nov 1 | Nov 2 | Nov 5 | Nov 8 | Nov 11 | Nov 14 | Nov 18 | Nov 24 |
| 28°F | Nov 5 | Nov 9 | Nov 12 | Nov 15 | Nov 18 | Nov 22 | Nov 25 | Nov 29 | Dec 4 |
| 24°F | Nov 12 | Nov 18 | Nov 22 | Nov 26 | Nov 30 | Dec 2 | Dec 6 | Dec 12 | Dec 19 |
| 20°F | Nov 21 | Nov 28 | Dec 2 | Dec 6 | Dec 10 | Dec 15 | Dec 20 | Dec 26 | Jan 2 |
| 16°F | Dec 1 | Dec 10 | Dec 15 | Dec 21 | Dec 26 | Dec 30 | Jan 3 | Jan 10 | Jan 17 |
Freeze probabilities 1991–2020 at Glenwillard Dashields L&D, 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 15003 →Compare Ambridge with another place →
Compared with the next station
The nearest other station, Moon Twp, PA, 4 miles south of Ambridge and 462 feet higher, has a last frost 20 days later (April 28), a first frost 21 days earlier (October 18), a season 40 days shorter.
When it snows in Ambridge, Pennsylvania
The first measurable snow (0.1 inch or more) in Ambridge usually arrives around December 24, and the last of the season around February 23. Those are the middle dates across the winters of 1991–2020 at Glenwillard Dashields L&D, PA, 3.2 miles away: half of years saw snow earlier, half later. Snow fell in 88% of those winters. The last 32°F night of spring typically comes 44 days after the last snow.
Planting calendar for 15003
| When | What to do |
|---|---|
| January 28 – February 11 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 11 – February 25 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 11 – March 25 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 8 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 16 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 25 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| November 8 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 15003 is 3 miles from Glenwillard Dashields L&D, PA, which stands at 710 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 4 other ZIP codes share the station; its figures are presented in full for 15001 (Aliquippa). The 2023 USDA Plant Hardiness Zone Map lists ZIP 15003 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.