Frost dates for 19002Ambler, PA
The average last spring frost in Ambler is April 11 and the average first fall frost is November 1, giving a typical growing season of about 205 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 11
- Average first fall frost
- Nov 1
- Growing season
- 205 days
Safer after Apr 27 (1-in-10 risk)
Possible by Oct 17 (1-in-10 risk)
First frost typically in 0 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | Apr 10 · Apr 24 · May 11 | Oct 6 · Oct 21 · Nov 4 | 179 days | 100% |
| Frost / freeze (32°F) | Mar 29 · Apr 11 · Apr 27 | Oct 17 · Nov 1 · Nov 17 | 205 days | 100% |
| Hard freeze (28°F) | Mar 15 · Mar 30 · Apr 12 | Nov 1 · Nov 13 · Dec 1 | 229 days | 100% |
Planting calendar for Ambler
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | Mar 11 – May 17 |
| Tomatoes | Transplant outdoors | Apr 27 – Jul 12 |
| Peppers | Start seeds indoors | Mar 11 – Apr 11 |
| Peppers | Transplant outdoors | May 11 – Jun 11 |
| Eggplant | Start seeds indoors | Mar 28 – Apr 26 |
| Eggplant | Transplant outdoors | May 11 – Jun 11 |
| Cucumbers | Sow outdoors | May 11 – Jul 22 |
| Summer squash | Sow outdoors | Apr 27 – Jun 11 |
| Winter squash & pumpkins | Sow outdoors | May 11 – Jun 11 |
| Snap beans | Sow outdoors | Apr 27 – Aug 14 |
| Sweet corn | Sow outdoors | Apr 27 – Jul 12 |
| Watermelon & cantaloupe | Sow outdoors | May 11 – Jun 11 |
| Okra | Sow outdoors | May 4 – May 27 |
| Peas | Sow outdoors (spring) | Mar 11 – Apr 26 |
| Potatoes | Plant outdoors (spring) | Mar 11 – May 11 |
| Onions | Start seeds indoors (spring) | Jan 28 – Feb 24 |
| Onions | Transplant outdoors (spring) | Mar 28 – Apr 26 |
| Broccoli | Start seeds indoors (spring) | Feb 21 – Mar 27 |
| Broccoli | Transplant outdoors (spring) | Mar 28 – Apr 26 |
| Broccoli | Start seeds indoors (fall) | Jul 2 – Jul 12 |
| Broccoli | Transplant outdoors (fall) | Aug 1 – Aug 12 |
| Cabbage | Start seeds indoors (spring) | Feb 11 – Mar 11 |
| Cabbage | Transplant outdoors (spring) | Mar 11 – Apr 11 |
| Cabbage | Start seeds indoors (fall) | Jun 22 – Jul 22 |
| Cabbage | Transplant outdoors (fall) | Jul 22 – Aug 22 |
| Leaf lettuce | Sow outdoors (spring) | Mar 11 – May 27 |
| Leaf lettuce | Sow outdoors (fall) | Jul 22 – Sep 7 |
| Spinach | Sow outdoors (spring) | Mar 4 – Apr 17 |
| Spinach | Sow outdoors (fall) | Aug 8 – Sep 12 |
| Radishes | Sow outdoors (spring) | Mar 11 – May 1 |
| Radishes | Sow outdoors (fall) | Jul 22 – Sep 22 |
| Kale | Sow outdoors (spring) | Mar 28 – Apr 17 |
| Kale | Sow outdoors (fall) | Jul 15 – Aug 22 |
| Carrots | Sow outdoors (spring) | Apr 11 – May 27 |
| Carrots | Sow outdoors (fall) | Jun 22 – Aug 7 |
| Garlic | Plant outdoors (fall) | Oct 22 – Nov 22 |
Where these dates come from
ZIP code 19002 is matched to the NOAA station Willow Grove Nas, PA, 6 km away, at 361 ft elevation (7 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Willow Grove Nas, PA (used) | 361 ft | Apr 11 | Nov 1 |
| Norristown, PA | 62 ft | Apr 8 | Oct 31 |
| Doylestown Ap, PA | 394 ft | Apr 13 | Oct 30 |
| Graterford 1 E, PA | 279 ft | Apr 24 | Oct 15 |
Frost dates near Ambler
- Spring House, PA 19477 · last Apr 11, first Nov 1
- Gwynedd Valley, PA 19437 · last Apr 11, first Nov 1
- Gwynedd, PA 19436 · last Apr 11, first Nov 1
- Fort Washington, PA 19034 · last Apr 11, first Nov 1
- Montgomeryville, PA 18936 · last Apr 11, first Nov 1
- North Wales, PA 19454 · last Apr 11, first Nov 1
- Blue Bell, PA 19424 · last Apr 11, first Nov 1
- Horsham, PA 19044 · last Apr 11, first Nov 1
Frequently asked questions
- When is the last frost in Ambler, PA?
- For ZIP code 19002, the average last spring frost (32°F) is April 11, based on NOAA 1991-2020 climate normals for the Willow Grove Nas, PA weather station. There is a 1-in-10 chance of a frost after April 27.
- When is the first frost in Ambler, PA?
- The average first fall frost (32°F) is November 1. There is a 1-in-10 chance of frost by October 17, so tender plants are at risk from that point on.
- How long is the growing season in 19002?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 205 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.