Mendham, NJ climate
Mendham has chilly winters and warm summers, with plenty of rain. A typical July afternoon reaches 84°, a January night drops to 20°, and about 30 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Mendham feels like
Winter
Spring
Summer
Fall
Mendham weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 38° | 20° | 3.8" | 7.4" | 11 | 11 | 20° – 36° |
| February | 41° | 22° | 3.0" | 10.3" | 8 | 14 | 19° – 38° |
| March | 49° | 29° | 4.2" | 5.8" | 10 | 6 | 33° – 48° |
| April | 61° | 38° | 4.1" | 0.7" | 10 | 0 | 46° – 55° |
| May | 71° | 48° | 4.2" | 0 | 12 | 0 | 55° – 65° |
| June | 80° | 57° | 4.9" | 0 | 12 | 0 | 65° – 71° |
| July | 84° | 62° | 4.9" | 0 | 11 | 0 | 69° – 77° |
| August | 83° | 60° | 4.6" | 0 | 10 | 0 | 67° – 75° |
| September | 76° | 54° | 4.7" | 0 | 9 | 0 | 62° – 69° |
| October | 64° | 42° | 4.7" | 0.3" | 9 | 0 | 48° – 60° |
| November | 53° | 33° | 3.6" | 0.3" | 9 | 0 | 38° – 48° |
| December | 42° | 25° | 4.6" | 4.8" | 10 | 5 | 27° – 45° |
| Year | 62° | 41° | 51.1" | 29.6" | 120 | 37 |
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain and snow in Mendham
Mendham gets 51 inches of rain and melted snow a year. July is the wettest month and February the driest. Rain or snow falls on about 120 days a year. Snow covers the ground about 37 days of the year.
About 176 frost-free days a year
In half of years the last 32° night comes by April 26 and the first one by October 18. That leaves about 176 frost-free days for gardens, shorter than 53% of U.S. towns.
Heating and cooling a home in Mendham
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Mendham, 86% of that work is heating and 14% is cooling, so the furnace matters far more than the air conditioner.
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
Mendham and its neighbors
Mendham borders 1 town with climate data. January nights across them vary by 0.5°. Mendham has both the coldest January nights (20°) and the hottest July afternoons (84°). Mendham’s January low is 20° and its July high 84°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Mendham compares
Compared with every U.S. town and city on TownTapestry, each counted once.
Warmer than it used to be
The last 30 years in Mendham averaged 2.2° warmer than the 1900s. The biggest change is in December (+3.7°). The shift is larger than in 97% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Mendham’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. February swings the most: between 1991 and 2020 its average temperature ranged from 19° to 38°. June is the most reliable, staying within 7°.
Common questions about Mendham’s climate
What is the coldest month in Mendham?
January, with a typical high of 38° and a low of 20°.
What is the hottest month in Mendham?
July, with a typical high of 84° and a low of 62°. About 23 days a year reach 90°.
How much snow does Mendham get?
About 30 inches in a normal winter, most of it in February.
When is the first frost in Mendham?
In half of years the first 32° night comes by October 18, and the last spring frost by April 26.
What is the rainiest month in Mendham?
July, with 4.9 inches of rain and melted snow. The year totals 51 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Mendham itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Pottersville 2 Nnw, NJ (7 mi, snow) and Somerville Somerset Airport, NJ (11 mi, frost, heat and degree days). Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.