USDA Hardiness Zone 7a
Frost Dates for 08525 — Hopewell, New Jersey
NOAA 1991–2020 normals from Wertsville 4 NE, NJ (283 ft), 5 miles north.
Updated
In Hopewell, the last spring frost (32°F) is around April 16 in half of years and has passed by May 1 in nine years out of ten. The first fall frost comes around October 27, as early as October 10 one year in ten, leaving a typical freeze-free season of 192 days (NOAA, Wertsville 4 NE, NJ).
- Last spring frost
- April 16
- First fall frost
- October 27
- Growing season
- 192 days
- Hardiness zone
- 7a
50% probability
50% probability
freeze-free, 50%
0 to 5°F (-17.8 to -15.0°C) coldest night
- First snow
- December 10
- Last snow
- March 16
- Winters with snow
- 100%
- Snow per year
- 23.9"
median, 1991–2020
median, 1991–2020
17 of 17 observed
NOAA normal
Frost risk by date in Hopewell
Half of springs at Wertsville 4 NE, NJ see their last 32°F night by April 16; only one in ten is past it by April 3, and one in ten still has one after May 1. Planting tender crops after April 21 leaves a 30% risk of a frost on them, after April 25 20%, and after May 1 10%. The 15 days between the even-odds date and the one-in-ten date is narrower than at 57% of the 56 New Jersey stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 27 in half of years, as early as October 10 one year in ten, and holds off past November 9 one year in ten. A hard freeze of 28°F follows 11 days later, around November 7; in spring the one-in-ten date for 28°F is April 16, 15 days before the 32°F one. The freeze-free season lasts 192 days in a typical year, shorter than at 52% of the 56 New Jersey stations; it reaches 213 days one year in ten and falls short of 171 one year in ten. On average 118 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 14 days longer, to about April 30, and return around October 14. Severe cold of 16°F or below comes every winter, usually between December 20 and March 2.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 15 | Apr 20 | Apr 23 | Apr 26 | Apr 30 | May 2 | May 5 | May 9 | May 15 |
| 32°F | Apr 3 | Apr 6 | Apr 9 | Apr 12 | Apr 16 | Apr 18 | Apr 21 | Apr 25 | May 1 |
| 28°F | Mar 20 | Mar 26 | Mar 30 | Apr 1 | Apr 3 | Apr 4 | Apr 7 | Apr 11 | Apr 16 |
| 24°F | Mar 8 | Mar 13 | Mar 17 | Mar 20 | Mar 24 | Mar 27 | Mar 30 | Apr 1 | Apr 4 |
| 20°F | Feb 24 | Mar 2 | Mar 5 | Mar 9 | Mar 13 | Mar 16 | Mar 19 | Mar 23 | Mar 28 |
| 16°F | Feb 10 | Feb 18 | Feb 24 | Feb 28 | Mar 2 | Mar 5 | Mar 9 | Mar 13 | Mar 18 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 1 | Oct 5 | Oct 8 | Oct 10 | Oct 14 | Oct 17 | Oct 21 | Oct 25 | Oct 30 |
| 32°F | Oct 10 | Oct 16 | Oct 20 | Oct 24 | Oct 27 | Oct 30 | Nov 1 | Nov 4 | Nov 9 |
| 28°F | Oct 25 | Oct 31 | Nov 2 | Nov 4 | Nov 7 | Nov 10 | Nov 13 | Nov 17 | Nov 23 |
| 24°F | Nov 5 | Nov 10 | Nov 13 | Nov 17 | Nov 20 | Nov 24 | Nov 28 | Dec 1 | Dec 7 |
| 20°F | Nov 14 | Nov 20 | Nov 25 | Nov 30 | Dec 2 | Dec 6 | Dec 12 | Dec 18 | Dec 26 |
| 16°F | Nov 29 | Dec 2 | Dec 8 | Dec 15 | Dec 20 | Dec 24 | Dec 29 | Jan 3 | Jan 11 |
Freeze probabilities 1991–2020 at Wertsville 4 NE, NJ, 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 08525 →Compare Hopewell with another place →
Weather by month in Hopewell
July is the warmest month at Wertsville 4 NE, NJ, averaging 85°F by day and 64°F at night; January is the coldest at 38°F and 22°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 11% of years.
Warmth for growing adds up to 3,232 growing degree days a year (base 50°F), fewer than at 73% of the 56 New Jersey stations. 33% of them (1,070) have built up by the end of June, and July adds the most, 766. Precipitation totals 51.1 inches a year, most in July (5.5") and least in February (3.0"); May to September bring 46% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 38 | 22 | 3.8 | 100% | 27 | 2 |
| Feb | 41 | 23 | 3.0 | 100% | 25 | 3 |
| Mar | 50 | 30 | 4.3 | 100% | 21 | 23 |
| Apr | 62 | 40 | 4.1 | 94% | 6 | 118 |
| May | 71 | 50 | 4.4 | 11% | <1 | 336 |
| Jun | 80 | 59 | 4.7 | 0% | 0 | 588 |
| Jul | 85 | 64 | 5.5 | 0% | 0 | 766 |
| Aug | 83 | 62 | 4.3 | 0% | 0 | 701 |
| Sep | 77 | 55 | 4.5 | 0% | 0 | 474 |
| Oct | 65 | 44 | 4.4 | 64% | 3 | 177 |
| Nov | 54 | 35 | 3.5 | 100% | 14 | 38 |
| Dec | 43 | 28 | 4.6 | 100% | 24 | 8 |
Monthly normals 1991–2020 at Wertsville 4 NE, NJ (283 ft), NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.
Compared with the next station
The nearest other station, Trenton Mercer Co Airport, NJ, 8 miles south of Hopewell, has a last frost 6 days earlier (April 10), a first frost 5 days later (November 1), a season 10 days longer.
When it snows in Hopewell, New Jersey
The first measurable snow (0.1 inch or more) in Hopewell usually arrives around December 10, and the last of the season around March 16. Those are the middle dates across the winters of 1991–2020 at Wertsville 4 NE, NJ, 4.5 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 31 days after the last snow.
Planting calendar for 08525
| When | What to do |
|---|---|
| February 5 – February 19 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 19 – March 5 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 19 – April 2 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 16 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 4 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 13 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 27 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 08525 is 5 miles from Wertsville 4 NE, NJ, which stands at 283 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 5 other ZIP codes share the station; its figures are presented in full for 08844 (Hillsborough). The 2023 USDA Plant Hardiness Zone Map lists ZIP 08525 in zone 7a, the band where the coldest night of the year averaged 0 to 5°F (-17.8 to -15.0°C) over 1991–2020; a zone describes winter lows, not frost dates.
Frost dates across New Jersey →
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.