USDA Hardiness Zone 7a
Frost Dates for 08869 — Raritan, New Jersey
NOAA 1991–2020 normals from Somerville 4 NW, NJ (134 ft), 3 miles north.
Updated
In Raritan, the last spring frost (32°F) is around April 30 in half of years and has passed by May 14 in nine years out of ten. The first fall frost comes around October 20, as early as October 5 one year in ten, leaving a typical freeze-free season of 172 days (NOAA, Somerville 4 NW, NJ).
- Last spring frost
- April 30
- First fall frost
- October 20
- Growing season
- 172 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 11
- Last snow
- March 24
- Winters with snow
- 100%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
15 of 15 observed
NOAA normal
Frost risk by date in Raritan
Half of springs at Somerville 4 NW, NJ see their last 32°F night by April 30; only one in ten is past it by April 15, and one in ten still has one after May 14. Planting tender crops after May 5 leaves a 30% risk of a frost on them, after May 9 20%, and after May 14 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 66% of the 56 New Jersey stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 20 in half of years, as early as October 5 one year in ten, and holds off past November 3 one year in ten. A hard freeze of 28°F follows 11 days later, around October 31; in spring the one-in-ten date for 28°F is May 1, 13 days before the 32°F one. The freeze-free season lasts 172 days in a typical year, shorter than at 91% of the 56 New Jersey stations; it reaches 193 days one year in ten and falls short of 151 one year in ten. On average 137 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 10 days longer, to about May 10, and return around October 9. Severe cold of 16°F or below comes every winter, usually between December 5 and March 7.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 27 | Apr 30 | May 4 | May 7 | May 10 | May 14 | May 16 | May 20 | May 24 |
| 32°F | Apr 15 | Apr 20 | Apr 24 | Apr 27 | Apr 30 | May 2 | May 5 | May 9 | May 14 |
| 28°F | Apr 1 | Apr 5 | Apr 8 | Apr 11 | Apr 15 | Apr 18 | Apr 22 | Apr 26 | May 1 |
| 24°F | Mar 16 | Mar 21 | Mar 25 | Mar 29 | Apr 1 | Apr 3 | Apr 5 | Apr 8 | Apr 15 |
| 20°F | Mar 2 | Mar 7 | Mar 11 | Mar 15 | Mar 18 | Mar 21 | Mar 25 | Mar 29 | Apr 1 |
| 16°F | Feb 19 | Feb 26 | Mar 1 | Mar 4 | Mar 7 | Mar 10 | Mar 13 | Mar 17 | Mar 22 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 28 | Oct 1 | Oct 4 | Oct 7 | Oct 9 | Oct 12 | Oct 16 | Oct 19 | Oct 24 |
| 32°F | Oct 5 | Oct 10 | Oct 13 | Oct 16 | Oct 20 | Oct 23 | Oct 27 | Nov 1 | Nov 3 |
| 28°F | Oct 15 | Oct 21 | Oct 25 | Oct 28 | Oct 31 | Nov 2 | Nov 5 | Nov 8 | Nov 12 |
| 24°F | Oct 28 | Nov 1 | Nov 4 | Nov 8 | Nov 10 | Nov 13 | Nov 16 | Nov 20 | Nov 26 |
| 20°F | Nov 7 | Nov 12 | Nov 16 | Nov 19 | Nov 22 | Nov 26 | Nov 30 | Dec 3 | Dec 9 |
| 16°F | Nov 16 | Nov 22 | Nov 29 | Dec 1 | Dec 5 | Dec 10 | Dec 16 | Dec 21 | Dec 26 |
Freeze probabilities 1991–2020 at Somerville 4 NW, 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 08869 →Compare Raritan with another place →
Weather by month in Raritan
July is the warmest month at Somerville 4 NW, NJ, averaging 86°F by day and 62°F at night; January is the coldest at 39°F and 19°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 44% of years.
Warmth for growing adds up to 2,964 growing degree days a year (base 50°F), fewer than at 88% of the 56 New Jersey stations. 32% of them (935) have built up by the end of June, and July adds the most, 733. Precipitation totals 46.8 inches a year, most in July (4.7") and least in February (2.8"); May to September bring 44% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 39 | 19 | 3.6 | 100% | 28 | 2 |
| Feb | 41 | 20 | 2.8 | 100% | 25 | 1 |
| Mar | 50 | 27 | 4.1 | 100% | 23 | 11 |
| Apr | 62 | 36 | 4.0 | 100% | 10 | 86 |
| May | 72 | 46 | 3.4 | 44% | 1 | 285 |
| Jun | 81 | 56 | 4.3 | 0% | 0 | 552 |
| Jul | 86 | 62 | 4.7 | 0% | 0 | 733 |
| Aug | 83 | 60 | 3.7 | 0% | 0 | 673 |
| Sep | 77 | 53 | 4.3 | 2% | 0 | 450 |
| Oct | 64 | 41 | 4.3 | 79% | 6 | 142 |
| Nov | 54 | 31 | 3.2 | 100% | 18 | 28 |
| Dec | 43 | 24 | 4.4 | 100% | 25 | 4 |
Monthly normals 1991–2020 at Somerville 4 NW, NJ (134 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, Somerville Somerset Airport, NJ, 4 miles northwest of Raritan, has a last frost 4 days earlier (April 26), a first frost 2 days earlier (October 18), a season 4 days longer.
When it snows in Raritan, New Jersey
The first measurable snow (0.1 inch or more) in Raritan usually arrives around December 11, and the last of the season around March 24. Those are the middle dates across the winters of 1991–2020 at Somerville 4 NW, NJ, 3.1 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 37 days after the last snow.
Planting calendar for 08869
| When | What to do |
|---|---|
| February 19 – March 5 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 5 – March 19 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 2 – April 16 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 30 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 28 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 6 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 20 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 08869 is 3 miles from Somerville 4 NW, NJ, which stands at 134 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 6 other ZIP codes share the station; its figures are presented in full for 08807 (Bridgewater). The 2023 USDA Plant Hardiness Zone Map lists ZIP 08869 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.