Frost dates for 08638Trenton, NJ
The average last spring frost in Trenton is April 10 and the average first fall frost is November 1, giving a typical growing season of about 202 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 10
- Average first fall frost
- Nov 1
- Growing season
- 202 days
Safer after Apr 25 (1-in-10 risk)
Possible by Oct 15 (1-in-10 risk)
Last frost typically in 158 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 25 · May 11 | Oct 6 · Oct 20 · Nov 2 | 176 days | 100% |
| Frost / freeze (32°F) | Mar 30 · Apr 10 · Apr 25 | Oct 15 · Nov 1 · Nov 13 | 202 days | 100% |
| Hard freeze (28°F) | Mar 16 · Mar 31 · Apr 12 | Oct 29 · Nov 12 · Nov 29 | 226 days | 100% |
Planting calendar for Trenton
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 10 – May 16 |
| Tomatoes | Transplant outdoors | Apr 26 – Jul 12 |
| Peppers | Start seeds indoors | Mar 10 – Apr 10 |
| Peppers | Transplant outdoors | May 10 – Jun 10 |
| Eggplant | Start seeds indoors | Mar 27 – Apr 25 |
| Eggplant | Transplant outdoors | May 10 – Jun 10 |
| Cucumbers | Sow outdoors | May 10 – Jul 22 |
| Summer squash | Sow outdoors | Apr 26 – Jun 10 |
| Winter squash & pumpkins | Sow outdoors | May 10 – Jun 10 |
| Snap beans | Sow outdoors | Apr 26 – Aug 14 |
| Sweet corn | Sow outdoors | Apr 26 – Jul 12 |
| Watermelon & cantaloupe | Sow outdoors | May 10 – Jun 10 |
| Okra | Sow outdoors | May 3 – May 26 |
| Peas | Sow outdoors (spring) | Mar 10 – Apr 25 |
| Potatoes | Plant outdoors (spring) | Mar 10 – May 10 |
| Onions | Start seeds indoors (spring) | Jan 27 – Feb 23 |
| Onions | Transplant outdoors (spring) | Mar 27 – Apr 25 |
| Broccoli | Start seeds indoors (spring) | Feb 20 – Mar 26 |
| Broccoli | Transplant outdoors (spring) | Mar 27 – Apr 25 |
| Broccoli | Start seeds indoors (fall) | Jul 2 – Jul 12 |
| Broccoli | Transplant outdoors (fall) | Aug 1 – Aug 12 |
| Cabbage | Start seeds indoors (spring) | Feb 10 – Mar 10 |
| Cabbage | Transplant outdoors (spring) | Mar 10 – Apr 10 |
| Cabbage | Start seeds indoors (fall) | Jun 22 – Jul 22 |
| Cabbage | Transplant outdoors (fall) | Jul 22 – Aug 22 |
| Leaf lettuce | Sow outdoors (spring) | Mar 10 – May 26 |
| Leaf lettuce | Sow outdoors (fall) | Jul 22 – Sep 7 |
| Spinach | Sow outdoors (spring) | Mar 3 – Apr 16 |
| Spinach | Sow outdoors (fall) | Aug 8 – Sep 12 |
| Radishes | Sow outdoors (spring) | Mar 10 – Apr 30 |
| Radishes | Sow outdoors (fall) | Jul 22 – Sep 22 |
| Kale | Sow outdoors (spring) | Mar 27 – Apr 16 |
| Kale | Sow outdoors (fall) | Jul 15 – Aug 22 |
| Carrots | Sow outdoors (spring) | Apr 10 – May 26 |
| Carrots | Sow outdoors (fall) | Jun 22 – Aug 7 |
| Garlic | Plant outdoors (fall) | Oct 22 – Nov 22 |
Where these dates come from
ZIP code 08638 is matched to the NOAA station Trenton Mercer Co Ap, NJ, 5.3 km away, at 184 ft elevation (79 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Trenton Mercer Co Ap, NJ (used) | 184 ft | Apr 10 | Nov 1 |
| Trenton State College, NJ | 100 ft | Apr 17 | Oct 28 |
| Hightstown 2 W, NJ | 100 ft | Apr 25 | Oct 16 |
| Lambertville, NJ | 68 ft | Apr 16 | Oct 19 |
Frost dates near Trenton
- Trenton, NJ 08618 · last Apr 10, first Nov 1
- Joint Base Mdl, NJ 08640 · last Apr 10, first Nov 1
- Lawrence Township, NJ 08648 · last Apr 10, first Nov 1
- Millstone Township, NJ 08535 · last Apr 10, first Nov 1
- Princeton, NJ 08543 · last Apr 25, first Oct 16
- Morrisville, PA 19067 · last Apr 10, first Nov 1
- Pennington, NJ 08534 · last Apr 10, first Nov 1
- Princeton Junction, NJ 08550 · last Apr 25, first Oct 16
Frequently asked questions
- When is the last frost in Trenton, NJ?
- For ZIP code 08638, the average last spring frost (32°F) is April 10, based on NOAA 1991-2020 climate normals for the Trenton Mercer Co Ap, NJ weather station. There is a 1-in-10 chance of a frost after April 25.
- When is the first frost in Trenton, NJ?
- The average first fall frost (32°F) is November 1. There is a 1-in-10 chance of frost by October 15, so tender plants are at risk from that point on.
- How long is the growing season in 08638?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 202 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.