Photo: Kenneth C. Zirkel · CC BY 4.0Dedham’s winters are colder and snowier than most of the U.S.
A typical July afternoon reaches 84°, a January night drops to 19°, and about 70 inches of snow falls in a normal winter.
A year in Dedham at a glance
Each month’s typical high and low, and what it brings.
What stands out about Dedham’s climate
Compared with towns across the U.S., with Dedham’s place in Massachusetts beside it.
What a year in Dedham feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 169 frost-free days a year
In half of years the last 32° night comes by April 27 and the first by October 14. Frost and day counts come from NOAA’s station at Walpole 2, MA, 7 miles from the town’s center, at about the same height.
The 2023 USDA map puts Dedham’s center in zone 6b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −2°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 70 inches of snow a winter
Snow, measured at Blue Hill Coop, MA, is heaviest from January through February, about 18 inches a month. Precipitation (rain plus melted snow) adds up to 49 inches a year; October is the wettest month and February the driest. Rain or snow falls on about 140 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Dedham
89% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through April.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Walpole 2, MA.
Living with Dedham’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
169 frost-free days in zone 6b. The last frost comes by Apr 27 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Oct 14.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August, September and October. 21 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Dedham from natural hazards, river flooding is the largest share (71%); heat waves, cold waves, winter storms and ice storms together are 6%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Dedham and its neighbors
Every town next door is within a degree of Dedham in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Dedham’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Dedham, MA | 19° | 84° | 49" | 70" |
| Johnstown, PA | 19° | 83° | 47" | 74" |
| Shawangunk, NY | 17° | 84° | 48" | 59" |
| Elkins, WV | 21° | 82° | 50" | 69" |
| Cortland, OH | 18° | 83° | 43" | 68" |
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.
Warmer than it used to be
The last 30 years in Dedham averaged 2.1° warmer than the 1900s. The biggest change is in December (+3.6°).
A bigger shift than in 92% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Dedham compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Dedham’s place among Massachusetts’.
Dedham weather by month
Highs, lows and precipitation from NOAA’s grid at Dedham’s center; snow, wet days and snow on the ground from Blue Hill Coop, MA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 37° | 19° | 3.8" | 18.6" | 13 | 17 | 19° – 35° |
| February | 40° | 20° | 3.4" | 18.2" | 11 | 16 | 17° – 37° |
| March | 47° | 27° | 4.7" | 15.0" | 13 | 12 | 32° – 45° |
| April | 59° | 37° | 4.3" | 2.8" | 13 | 1 | 44° – 52° |
| May | 70° | 47° | 3.7" | 0.0" | 13 | 0 | 52° – 63° |
| June | 78° | 56° | 4.2" | 0.0" | 12 | 0 | 63° – 70° |
| July | 84° | 62° | 3.5" | 0.0" | 11 | 0 | 68° – 77° |
| August | 82° | 61° | 3.7" | 0.0" | 10 | 0 | 68° – 76° |
| September | 75° | 53° | 4.0" | 0.0" | 9 | 0 | 60° – 67° |
| October | 63° | 41° | 4.9" | 0.7" | 12 | 0 | 49° – 59° |
| November | 52° | 33° | 4.1" | 1.8" | 11 | 1 | 37° – 47° |
| December | 42° | 24° | 4.8" | 12.6" | 13 | 9 | 27° – 43° |
| Year | 61° | 40° | 49.1" | 69.7" | 140 | 56 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 17° to 37°. June is the most reliable, staying within 7°.
Where Dedham’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Dedham’s center.
- Snow: Blue Hill Coop, MA.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Walpole 2, MA, 7 miles from the town’s center, at about the same height; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Dedham’s climate
What is the weather like in Dedham?
A typical July afternoon reaches 84°, a January night drops to 19°, and about 70 inches of snow falls in a normal winter. Colder January nights than 66% of U.S. towns; cooler July afternoons than 62% of U.S. towns.
How cold does it get in Dedham in winter?
January nights average 19°. About 127 nights a year reach 32° or below and 3 reach 0° or below. In the coldest January of the last 30 years the month averaged 19°.
How much snow does Dedham get?
About 70 inches in a normal winter at Blue Hill Coop, MA, heaviest from January through February, about 18 inches a month, with snow on the ground about 56 days a year.
How hot does it get in Dedham?
July, with a typical high of 84° and a low of 62°. About 13 days a year reach 90° (Walpole 2, MA).
When is the first and last frost in Dedham?
In half of years the last spring frost (32°) comes by April 27 and the first fall frost by October 14, about 169 frost-free days, at Walpole 2, MA.
What growing zone is Dedham in?
Zone 6b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −2°.
What is the best time of year to visit Dedham?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, July, August, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Dedham getting warmer?
Yes: 1991–2020 averaged 2.1° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 92% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Dedham.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.