Iselin, New Jersey Weather
Fireflies rise from the lawn. Day 77 of spring. Read this microseason across nine climate regions →
Iselin weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 3Mostly Clear——85°58°—
- ThursdayJun 4Overcast——89°61°+4°
- FridayJun 5Overcast——90°64°+1°
- SaturdayJun 6Light Drizzle15%—91°69°+1°
- SundayJun 7Heavy Drizzle65%—91°70°0°
- MondayJun 8Light Drizzle38%—76°62°-15°
- TuesdayJun 9Overcast15%—89°58°+13°
Ozone at AQI 49 now. AQI up 26 in the last 6 hours — air quality is degrading. With UV 0.0 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 12 by mid-afternoon.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.
What's driving it
Ozone × UV × Sky
Ozone at AQI 49 now. With UV 0.0 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 12 by mid-afternoon.
- Present
- AQI 49
- UV peak
- 0.0 at 1 PM
- Sky at peak
- clear
- Projected peak
- AQI 12
PM × Wind × Precip
PM2.5 at 7.6 µg/m³, PM10 at 8.5 µg/m³ — typical background levels with no transport signature.
- PM2.5/PM10
- 0.89
- Wind
- light
- Recent rain
- 0h in last 6h
- Pattern
- background
Trends
Seven days of AQI and PM2.5.
Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).
A summer fog for fair, a winter fog for rain.
- Moonrise
- 3:27 AM
- Moonset
- 12:55 PM
- In sign
- ♑︎ Capricorn
Fireflies rise from the lawn
Iselin at a glance
- Today vs. normal: 3°F below the seasonal normal for this latitude
- Last frost: April 19 (climatological average for this latitude)
- Microseason: Jun 1–5
- Planting window: Harvest spring lettuce before it bolts. Sow heat-tolerant greens.
Right now in the garden
Peak growing season
As of June 4, the growing season is at its peak — frost is months away. Continue succession-planting beans and summer squash. Start fall brassicas (broccoli, cabbage, kale) from seed indoors for transplanting in late summer.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| January | — | — |
| February | — | — |
| March | — | — |
| April | lettuce, peas, spinach, radishes | — |
| May | lettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| June | tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| July | tomatoes, peppers, beans, squash | tomatoes, beans, summer squash |
| August | — | tomatoes, beans, summer squash |
| September | fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| October | fall brassicas, garlic (overwinter), carrots | winter squash, tomatoes (last) |
| November | — | — |
| December | — | — |
A year in weather
Iselin's warmest month is July (~78°F mean) and its coldest is January (~33°F). Rainfall peaks in July (4.7 inches) and bottoms out in February (3.0 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 33° | 3.4″ | 6 |
| February | 35° | 3.0″ | 6 |
| March | 43° | 4.1″ | 7 |
| April | 53° | 3.9″ | 6 |
| May | 63° | 4.0″ | 7 |
| June | 73° | 4.3″ | 7 |
| July | 78° | 4.7″ | 7 |
| August | 76° | 4.2″ | 7 |
| September | 69° | 3.8″ | 6 |
| October | 58° | 3.8″ | 6 |
| November | 47° | 3.3″ | 5 |
| December | 38° | 4.1″ | 7 |
Regional context
Iselin sits within a warm-summer humid continental climate region — a cohort that shares similar temperature ranges, seasonal patterns, and growing conditions across nearby cities.
Similar climates: Trenton, NJ, Newark, NJ, Jersey City, NJ, Paterson, NJ, Elizabeth, NJ.
Frequently asked
- When does it freeze in Iselin?
- Iselin's last spring frost typically falls around mid-April, and the first fall frost arrives around mid-November.
- What is the rainy season in Iselin?
- July is the wettest month with about 4.7 inches of rain on average; the city receives roughly 47 inches annually.
- What is the warmest month in Iselin?
- July is typically warmest, averaging about 78°F.
- What is the coldest month in Iselin?
- January is typically coldest, averaging about 33°F.
- When can I start a vegetable garden in Iselin?
- Cool-season crops (peas, lettuce) can be sown around the last spring frost (mid-April); warm-season crops (tomatoes, peppers) wait until 1–2 weeks after.
- How many rainy days does Iselin get?
- Iselin averages about 76 rainy days per year.
- What hardiness zone is Iselin?
- Iselin's USDA hardiness zone is determined by its lowest average winter temperature; check the USDA's online lookup with the city ZIP for the current zone designation.
Climate
Iselin, New Jersey sits in a warm-summer humid continental climate zone. January means hover near 33°F while July averages 78°F — a 45°F seasonal swing.
Across the year, Iselin receives about 47 inches of precipitation spread over roughly 76 rainy days.
The rhythm of the year is set by latitude (40.6°N), proximity to large water bodies, and elevation — all of which shape what grows here, when frost is likely, and what the weather story looks like day to day.
Beaches near Iselin
- Jacob Riis Beach23.2 mi
- Rockaway Beach Beach25.3 mi
Each linked page shows live water temperature, wave height, swim and surf verdicts, tides, and rip-current risk from NDBC + NOAA + NWS data.