South Dennis has chilly winters and pleasant summers
A typical July afternoon reaches 79°, a January night drops to 24°, and about 22 inches of snow falls in a normal winter.
A year in South Dennis at a glance
Each month’s typical high and low, and what it brings.
What stands out about South Dennis’s climate
Read from where South Dennis sits among Massachusetts’s towns. The page puts what stands out first.
22 inches of snow, 45 of rain and melt
December is the wettest month and July the driest. Rain or snow falls on about 113 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
What a year in South Dennis feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
Living with South Dennis’s climate
What the numbers mean for a garden, a driveway, a furnace and a free afternoon.
204 frost-free days. The last frost comes by Apr 13 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Nov 3.
About 22" a winter over 5 days with an inch or more, most in January. Snow covers the ground about 16 days a year.
Months averaging under 55° run from October through April. Heating is 93% of the year’s heating-and-cooling load.
90° days are rare: July afternoons average 79°.
The nicest months are May, June, July, August, September and October. 19 miles of trails are waiting.
Parks & trails →Normals are averages. Ice storms, nor’easters, floods and heat waves are on the natural hazards page.
Natural hazards →Warmer than it used to be
The last 30 years in South Dennis averaged 2.0° warmer than the 1900s. The biggest change is in December (+3.5°).
A bigger shift than in 95% of U.S. towns.
Change by month
About 204 frost-free days a year
In half of years the last 32° night comes by April 13 and the first by November 3.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
South Dennis and its neighbors
South Yarmouth has the coldest January nights next door (24°) and Yarmouth the hottest July afternoons (79°). Tap a town to see its climate.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
How South Dennis compares
Against every U.S. town on TownTapestry, each counted once, with its place in Massachusetts.
South Dennis 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 | 39° | 24° | 3.9" | 9.5" | 10 | 5 | 23° – 38° |
| February | 40° | 25° | 3.3" | 6.3" | 10 | 7 | 23° – 38° |
| March | 45° | 30° | 4.4" | 3.6" | 10 | 3 | 32° – 43° |
| April | 54° | 38° | 4.1" | 0 | 11 | 0 | 42° – 49° |
| May | 63° | 47° | 3.2" | 0 | 10 | 0 | 50° – 59° |
| June | 72° | 56° | 3.3" | 0 | 9 | 0 | 60° – 68° |
| July | 79° | 63° | 2.5" | 0 | 7 | 0 | 67° – 75° |
| August | 78° | 62° | 3.4" | 0 | 8 | 0 | 67° – 74° |
| September | 72° | 56° | 3.8" | 0 | 8 | 0 | 61° – 67° |
| October | 62° | 46° | 4.4" | 0 | 10 | 0 | 51° – 60° |
| November | 53° | 38° | 4.0" | 0 | 10 | 0 | 41° – 49° |
| December | 44° | 30° | 4.7" | 2.1" | 12 | 2 | 31° – 46° |
| Year | 58° | 43° | 45.0" | 21.5" | 113 | 16 |
Heating and cooling a home in South Dennis
93% of the work is heating, so the furnace matters far more than the air conditioner.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. Source: NOAA station normals.
How much a month can swing
A normal is an average. January swings the most: from 1991 to 2020 its average ranged from 23° to 38°. September is the most reliable, staying within 7°.
Common questions about South Dennis’s climate
What is the coldest month in South Dennis?
January, with a typical high of 39° and a low of 24°.
What is the hottest month in South Dennis?
July, with a typical high of 79° and a low of 63°.
How much snow does South Dennis get?
About 22 inches in a normal winter, most of it in January.
When is the first frost in South Dennis?
In half of years the first 32° night comes by November 3, and the last spring frost by April 13.
What is the rainiest month in South Dennis?
December, with 4.7 inches of rain and melted snow. The year totals 45 inches.
Neighbors talk weather
Gardens, snow, and the best days of the year in South Dennis.
Your answer becomes a post in Town Square.
Temperatures and rainfall come from NOAA’s gridded climate normals for South Dennis itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Hyannis, MA (8 mi, snow) and West Harwich, MA (3 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. Today’s forecast: National Weather Service.