Allentown, NJ Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Allentown, a borough in Mercer County, New Jersey.
Today
85°F
Mostly Sunny
Mostly sunny, with a high near 85. East wind 0 to 5 mph.
7-day forecast for Allentown
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 85°F | Mostly Sunny | 0 to 5 mph E | 0% |
| Tonight | 64°F | Mostly Cloudy | 0 to 5 mph E | 3% |
| Wednesday | 85°F | Chance Rain Showers then Chance Showers And Thunderstorms | 0 to 5 mph E | 56% |
| Wednesday Night | 71°F | Chance Showers And Thunderstorms | 0 to 5 mph S | 54% |
| Thursday | 89°F | Slight Chance Rain Showers then Chance Showers And Thunderstorms | 5 to 10 mph SW | 27% |
| Thursday Night | 72°F | Chance Showers And Thunderstorms | 5 mph SW | 27% |
| Friday | 90°F | Mostly Sunny then Chance Showers And Thunderstorms | 5 mph SW | 41% |
| Friday Night | 71°F | Chance Showers And Thunderstorms | 0 to 5 mph SW | 46% |
| Saturday | 88°F | Partly Sunny then Chance Showers And Thunderstorms | 0 to 5 mph W | 37% |
| Saturday Night | 70°F | Chance Showers And Thunderstorms | 0 to 5 mph SW | 37% |
| Sunday | 89°F | Mostly Sunny then Slight Chance Showers And Thunderstorms | 0 to 5 mph W | 15% |
| Sunday Night | 71°F | Slight Chance Showers And Thunderstorms then Partly Cloudy | 0 to 5 mph SW | 15% |
| Monday | 90°F | Sunny | 0 to 10 mph W | 9% |
| Monday Night | 70°F | Slight Chance Showers And Thunderstorms | 5 mph W | 15% |
Forecast source: National Weather Service (api.weather.gov) for Allentown (40.179, -74.590). Updated through the day.
Growing snapshot for Allentown
Last spring frost
Apr 25
First fall frost
Oct 16
Growing season
173 days
Hardiness zone
7a
More local growing data for Allentown: nearby ZIP 08691 weather · frost dates · planting calendar · New Jersey frost dates
Nearby towns & communities
Groveville
Hamilton Square
Hightstown
Hopewell
Lawrenceville
Mercerville
Pennington
Princeton
Robbinsville Center
The College of New Jersey
Titusville
Trenton
Twin Rivers
White Horse
Windsor
Yardville
Climate data from the nearest NOAA station, Hightstown 2 W, Nj (4.5 mi from Allentown). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.