Deep River, CT climate
Deep River has chilly winters and pleasant summers, with plenty of rain. A typical July afternoon reaches 83°, a January night drops to 21°, and about 28 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Deep River feels like
Winter
Spring
Summer
Fall
Deep River 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° | 21° | 3.7" | 9.0" | 11 | 10 | 21° – 35° |
| February | 40° | 22° | 3.1" | 7.1" | 10 | 10 | 18° – 37° |
| March | 48° | 29° | 4.2" | 5.0" | 10 | 4 | 33° – 46° |
| April | 59° | 38° | 4.3" | 0.8" | 11 | 0 | 45° – 53° |
| May | 69° | 47° | 3.7" | 0 | 11 | 0 | 53° – 62° |
| June | 78° | 57° | 4.2" | 0 | 10 | 0 | 64° – 70° |
| July | 83° | 63° | 3.5" | 0 | 9 | 0 | 69° – 76° |
| August | 81° | 62° | 3.9" | 0 | 9 | 0 | 68° – 75° |
| September | 74° | 54° | 4.2" | 0 | 9 | 0 | 62° – 69° |
| October | 64° | 43° | 4.6" | 0 | 10 | 0 | 50° – 60° |
| November | 53° | 34° | 3.9" | 0.3" | 9 | 0 | 39° – 47° |
| December | 43° | 26° | 4.4" | 5.6" | 11 | 6 | 28° – 45° |
| Year | 61° | 41° | 47.7" | 27.8" | 120 | 30 |
“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 Deep River
Deep River gets 48 inches of rain and melted snow a year. October is the wettest month and February the driest. Rain or snow falls on about 120 days a year. Snow covers the ground about 30 days of the year.
About 175 frost-free days a year
In half of years the last 32° night comes by April 26 and the first one by October 16. That leaves about 175 frost-free days for gardens, shorter than 54% of U.S. towns.
Heating and cooling a home in Deep River
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Deep River, 89% of that work is heating and 11% 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.
Deep River and its neighbors
Deep River borders 4 towns with climate data. January nights across them vary by 1.4°. Chester has the coldest January nights (20°) and Lyme the hottest July afternoons (83°). Deep River’s January low is 21° and its July high 83°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Deep River 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 Deep River averaged 1.9° warmer than the 1900s. The biggest change is in December (+3.5°). The shift is larger than in 91% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Deep River’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 18° to 37°. June is the most reliable, staying within 6°.
Common questions about Deep River’s climate
What is the coldest month in Deep River?
January, with a typical high of 38° and a low of 21°.
What is the hottest month in Deep River?
July, with a typical high of 83° and a low of 63°. About 15 days a year reach 90°.
How much snow does Deep River get?
About 28 inches in a normal winter, most of it in January.
When is the first frost in Deep River?
In half of years the first 32° night comes by October 16, and the last spring frost by April 26.
What is the rainiest month in Deep River?
October, with 4.6 inches of rain and melted snow. The year totals 48 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Deep River itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Norwich Public Utility Plt, CT (24 mi, snow) and Meriden Markham Municipal Airport, CT (21 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.