Last spring frost
Apr 25
Frost Dates for Altoona, PA
First fall frost
Oct 21
Growing season
176 days
Hardiness zone
6b
In an average year around Altoona, PA, the last spring frost (32°F) is about Apr 25 and the first fall frost is about Oct 21, giving roughly a 176-day growing season. To be safe most years, wait until Apr 10 before setting out tender plants.
Last spring frost
Dates the last frost of spring typically ends. Plant tender crops after the risk has passed for your comfort level.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | May 22 | May 4 | Apr 21 |
| Freeze (32°F) | May 11 | Apr 25 | Apr 10 |
| Hard (28°F) | May 1 | Apr 13 | Apr 1 |
| Severe (24°F) | Apr 14 | Apr 2 | Mar 19 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 22 | May 17 | May 12 | May 8 | May 4 | May 1 | Apr 29 | Apr 25 | Apr 21 |
| 32°F | May 11 | May 6 | May 1 | Apr 29 | Apr 25 | Apr 22 | Apr 19 | Apr 15 | Apr 10 |
| 28°F | May 1 | Apr 24 | Apr 19 | Apr 16 | Apr 13 | Apr 9 | Apr 6 | Apr 4 | Apr 1 |
| 24°F | Apr 14 | Apr 10 | Apr 7 | Apr 4 | Apr 2 | Mar 31 | Mar 29 | Mar 24 | Mar 19 |
| 20°F | Apr 5 | Apr 1 | Mar 30 | Mar 27 | Mar 24 | Mar 21 | Mar 17 | Mar 13 | Mar 8 |
| 16°F | Mar 28 | Mar 23 | Mar 20 | Mar 17 | Mar 14 | Mar 11 | Mar 7 | Mar 3 | Feb 25 |
First fall frost
Dates the first frost of fall typically arrives. Count back by a crop's days-to-maturity to know your planting cutoff.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | Sep 26 | Oct 8 | Oct 21 |
| Freeze (32°F) | Oct 5 | Oct 21 | Nov 5 |
| Hard (28°F) | Oct 19 | Nov 3 | Nov 17 |
| Severe (24°F) | Nov 3 | Nov 15 | Nov 29 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 26 | Sep 30 | Oct 3 | Oct 6 | Oct 8 | Oct 11 | Oct 14 | Oct 17 | Oct 21 |
| 32°F | Oct 5 | Oct 10 | Oct 15 | Oct 18 | Oct 21 | Oct 24 | Oct 27 | Nov 1 | Nov 5 |
| 28°F | Oct 19 | Oct 24 | Oct 29 | Nov 1 | Nov 3 | Nov 6 | Nov 9 | Nov 13 | Nov 17 |
| 24°F | Nov 3 | Nov 6 | Nov 9 | Nov 12 | Nov 15 | Nov 18 | Nov 21 | Nov 25 | Nov 29 |
| 20°F | Nov 10 | Nov 15 | Nov 18 | Nov 22 | Nov 25 | Nov 28 | Dec 1 | Dec 5 | Dec 11 |
| 16°F | Nov 19 | Nov 26 | Nov 30 | Dec 3 | Dec 7 | Dec 10 | Dec 16 | Dec 21 | Dec 27 |
Growing season is measured at 32°F with about 50% probability. Hardiness zone from the 2023 USDA map; frost normals from NOAA 1991-2020.
Where this data comes from
@endif These dates are computed from the nearest official weather station with long-term records: Altoona 3 W, Pa, about 6.3 miles away@if(!empty($station['elevation_ft'])), at 1,320 ft elevation. The further the station and the greater the elevation difference from your yard, the more your local frost timing can vary.
How we calculate these dates
Frost and freeze dates come from the NOAA 1991–2020 U.S. Climate Normals, the National Oceanic and Atmospheric Administration's 30-year averages for each weather station. A date shown at the 50% level is the median: in half of years the frost falls on or before it. The 10% and 90% columns show the early and late ends of the range, so you can plant on the odds you're comfortable with. These are long-term averages, not a forecast for this year - always check your local outlook before planting.
Source: NOAA National Centers for Environmental Information, 1991–2020 Climate Normals (public domain). Harman is not affiliated with or endorsed by NOAA.
Frequently asked questions
When is the last frost in Altoona, PA?
On average, the last spring frost (32°F) around Altoona, PA is about Apr 25. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 10.
When is the first frost in the fall?
The first fall frost around Altoona, PA typically arrives about Oct 21. Count back by a crop's days to maturity to find the latest date you can plant it.
When can I plant tomatoes and other tender crops?
Tender crops like tomatoes, peppers and basil are damaged by frost, so wait until the last spring frost has passed - around Apr 25 on average, or Apr 10 to be safe most years.
How long is the growing season here?
The frost-free growing season (between the last spring and first fall 32°F frost) is about 176 days in a typical year.
Are these dates a forecast for this year?
No. They are 30-year averages from the NOAA 1991–2020 Climate Normals, not a prediction for the current year. Use them for planning and always check your local weather forecast before planting or protecting crops.
Local weather for 16601 Planting calendar → Pennsylvania frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026