Iselin (NJ) Weather & Climate: Best Time to Visit
Average temperatures, rainfall, sunshine and the best time to visit Iselin.
Climate overview of Iselin
Iselin, New Jersey, United States of America, sees big temperature differences between seasons, with July peaking at 31°C (88°F) and January dropping to 5°C (41°F).
Rain/snowfall is high, totalling around 1238 mm (49 in) per year. December is the wettest month and November the driest. The city also experiences very warm summers and cold winters. The most sunshine falls in July, with an average of 9.0 hours of daily sunshine.
Iselin Weather by Month
Pick a month to see the average temperature, rainfall and sunshine in Iselin - and find the best time to visit.
Monthly Temperature in Iselin
Visitors to Iselin can expect significant temperature changes throughout the year. Average maximum daytime temperatures range from a very warm 31°C (88°F) in July, the warmest time of the year, to a chilly 5°C (41°F) during cooler months like January.
At night, you can expect temperatures ranging from 20°C (68°F) in July to around -5°C (23°F) during January.
Check out our detailed temperature page for more information.
Temperature ranges by month
Rainfall in Iselin
Iselin is known for its substantial rain/snowfall, with annual precipitation reaching 1238 mm (49 in). While rainfall varies throughout the year, each season offers its own charm. December brings wetter days averaging 128 mm (5 in) of precipitation, spread over 11 rainy days.
In contrast, the driest month November experiences a drier climate, with about 75 mm (3 in) of rainfall spread across 9 rainy days. For more details, please visit our Iselin Precipitation page.
The mean monthly precipitation over the year, including rain, hail, and snow
The average number of days each month with precipitation
Sunshine Hours in Iselin
Seasonal changes in sunshine hours are quite dramatic in Iselin. While July receives considerable daily sunshine with up to 9.0 hours, December marks the darkest time of the year, where sunshine is scarce with only 4.7 hours of sunlight per day.
Visit our detailed sunshine hours page for more information.
Monthly hours of sunshine
Daily hours of sunshine
Daily percentage of sunshine
Humidity in Iselin by Month
The relative humidity is high throughout the year in Iselin.
The city experiences its highest humidity in September, reaching 68%. In April, the humidity drops to its lowest level at 55%. What does this mean? Read our detailed page on humidity levels for further details.
Relative humidity over the year
Best Time to Visit Iselin
Each month is rated for comfortable sightseeing weather — mild temperatures and low rainfall. Tap a month for its full averages; your ideal time may differ for a beach or winter trip (see below).
- Best overall: September
- Warmest weather: July and August
- Most sunshine: May, June, July and August
- Fewer rainy days: January, February, March, September and November
- Climate seasons: very warm summers and cold winters
- Best for winter weather: January, with freezing nights around -5°C (23°F).
Frequently asked questions about the climate in Iselin
What is the best time to visit Iselin?
September typically offers the most optimal weather in Iselin. In contrast, January, February, March and December tend to have less optimal conditions. Iselin has very warm summers and cold winters.
What temperatures can I expect in Iselin?
Daytime highs range from 5°C (41°F) in January to 31°C (88°F) in July. Nighttime lows range from -5°C (23°F) to 20°C (68°F). Temperatures vary considerably through the year.
How much rain does Iselin get?
Annual rainfall is around 1238 mm (49 in). December is the wettest month with 128 mm (5 in), while November is the driest with 75 mm (3 in).
How sunny is Iselin?
Iselin receives around 2,544 hours of sunshine per year. July is the sunniest month with 271 hours, while December is the cloudiest with just 141 hours. Overall, Iselin enjoys abundant sunshine.
Iselin 3-Day Forecast
Iselin (NJ) 3-Day Forecast
Iselin on the map
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