National Oceanic and Atmospheric Administration National Weather Service United States Department of Commerce

Dangerous Heat and Heavy Rainfall into the Weekend

Hot temperatures and high humidity are forecast to continue across the mid-Mississippi Valley into this weekend. Heat Advisories remain in effect. Heavy to excessive rainfall occurring at times through the weekend could bring areas of flooding to parts of the northern Rockies, upper Midwest, central Great Lakes, and southern New England. Read More >

Current conditions at

Trenton-Mercer Airport (KTTN)

Lat: 40.28°NLon: 74.82°WElev: 210ft.

Fair

74°F

23°C

Humidity 56%
Wind Speed N 6 mph
Barometer 30.07 in (1017.4 mb)
Dewpoint 57°F (14°C)
Visibility 10.00 mi
Last update 18 Sep 7:53 pm EDT
Extended Forecast for

Princeton NJ

  • Tonight

    Tonight: Partly cloudy, with a low around 56. North wind around 5 mph.

    Low: 56 °F

    Partly Cloudy

  • Saturday

    Saturday: Mostly sunny, with a high near 71. Northeast wind around 5 mph.

    High: 71 °F

    Mostly Sunny

  • Saturday Night

    Saturday Night: Patchy fog after 9pm. Otherwise, mostly cloudy, with a low around 60. Southeast wind around 5 mph.

    Low: 60 °F

    Patchy Fog

  • Sunday

    Sunday: Showers likely, then showers and possibly a thunderstorm after 2pm. Some of the storms could produce heavy rainfall. High near 73. South wind 5 to 10 mph. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

    High: 73 °F

    Heavy Rain

  • Sunday Night

    Sunday Night: Showers and possibly a thunderstorm before 2am, then a chance of showers. Some of the storms could produce heavy rainfall. Patchy fog. Low around 60. South wind around 5 mph becoming north after midnight. Chance of precipitation is 90%. New rainfall amounts between a half and three quarters of an inch possible.

    Low: 60 °F

    Heavy Rain
    and Patchy
    Fog

  • Monday

    Monday: A chance of showers. Mostly cloudy, with a high near 67. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.

    High: 67 °F

    Chance
    Showers

  • Monday Night

    Monday Night: A chance of showers. Mostly cloudy, with a low around 55. Chance of precipitation is 30%.

    Low: 55 °F

    Chance
    Showers

  • Tuesday

    Tuesday: A chance of showers. Mostly cloudy, with a high near 63. Chance of precipitation is 30%.

    High: 63 °F

    Chance
    Showers

  • Tuesday Night

    Tuesday Night: A chance of showers after 2am. Mostly cloudy, with a low around 52. Chance of precipitation is 30%.

    Low: 52 °F

    Mostly Cloudy
    then Chance
    Showers

Detailed Forecast

Tonight
Partly cloudy, with a low around 56. North wind around 5 mph.
Saturday
Mostly sunny, with a high near 71. Northeast wind around 5 mph.
Saturday Night
Patchy fog after 9pm. Otherwise, mostly cloudy, with a low around 60. Southeast wind around 5 mph.
Sunday
Showers likely, then showers and possibly a thunderstorm after 2pm. Some of the storms could produce heavy rainfall. High near 73. South wind 5 to 10 mph. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Sunday Night
Showers and possibly a thunderstorm before 2am, then a chance of showers. Some of the storms could produce heavy rainfall. Patchy fog. Low around 60. South wind around 5 mph becoming north after midnight. Chance of precipitation is 90%. New rainfall amounts between a half and three quarters of an inch possible.
Monday
A chance of showers. Mostly cloudy, with a high near 67. Chance of precipitation is 40%. New precipitation amounts between a tenth and quarter of an inch possible.
Monday Night
A chance of showers. Mostly cloudy, with a low around 55. Chance of precipitation is 30%.
Tuesday
A chance of showers. Mostly cloudy, with a high near 63. Chance of precipitation is 30%.
Tuesday Night
A chance of showers after 2am. Mostly cloudy, with a low around 52. Chance of precipitation is 30%.
Wednesday
A chance of showers. Mostly cloudy, with a high near 62. Chance of precipitation is 30%.
Wednesday Night
A chance of showers. Mostly cloudy, with a low around 51. Chance of precipitation is 40%.
Thursday
A chance of showers. Mostly cloudy, with a high near 62. Chance of precipitation is 30%.
Thursday Night
A chance of showers. Mostly cloudy, with a low around 51. Chance of precipitation is 30%.
Friday
Partly sunny, with a high near 67.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Princeton NJ
 40.37°N 74.67°W (Elev. 256 ft)
Last Update:
4:10 pm EDT Sep 18, 2026
Forecast Valid:
8pm EDT Sep 18, 2026-6pm EDT Sep 25, 2026
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

Link to Local Radar Data Link to Satellite Data

Hourly Weather Forecast

National Digital Forecast Database

National Digital Forecast Database Maximum Temperature Forecast

High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation