Chatham, MA Climate: Temperature & Rain by Month
Temperature and precipitation from NOAA NCEI 1991–2020 normals →, plus PlainClimate's derived comfort score
30-year climate normals (1991-2020) from Chatham's primary NOAA station, CHATHAM.
The climate verdict for Chatham
Water is the standout signal in Chatham, Massachusetts: 45.9 inches of precipitation in a normal year. Against that wet profile, NOAA records an annual average of 50°F. Its climate comfort score of 63/100 (good) lands mid-pack nationally, exceeding 46% of station-mapped location scores.
- 50°F
- annual average temperature (NOAA normal)
- 63/100
- comfort score, above 46% of station-mapped location scores
- 45.9"
- annual precipitation · 25" snow
- 224 days
- growing season, frost-free days
Chatham: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USC00191386 · Chatham, MA 50°F mean · 45.9" precip
TEMP-COOL · RANK-MID · PHOTO-FINISH · PRCP-MID · SWING-MID · COMF-MID · LOAD-HEAT · STN-1 · BOOK-FULL
- TEMP-COOL 50°F
- RANK-MID #2,813
- PHOTO-FINISH ≈ Valmora
- PRCP-MID 45.9"
- SWING-MID 38°F
- COMF-MID 63/100
- LOAD-HEAT 5,681 HDD
- STN-1 USC00191386
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Valmora, NM (+ 0 °F mean)
Instrument codes from this station's NOAA 1991–2020 normals, mean temperature, corpus warmth rank, photo-finish peer station, precipitation band, seasonal swing, comfort composite, degree-day load, and field book, not a livability rating.
Mean-temperature neighbourhood
Nationwide NOAA normal poles and nearest peers, not a reprint of every MA station list.
- Chatham (this station) 50°F
- Cold Heber (black Me…, AZ 50°F
- Hot Bowman Dam, CA 50°F
- Near Valmora, NM 50°F
- Near Doyle, CA 50°F
Climate Living Index · Chatham
Chatham: 60/100 · grade C
Chatham publishes 5 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 1 missing weight rescale to 100.
PlainClimate-derived for Chatham, not an official NOAA rating. Rankings still use Comfort Score 63/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Frost-free season | 224 days/year | 79/100 · B |
| Normal heat + freeze calendar | 100 calendar days | 76/100 · B |
| Precipitation balance | 45.9 in · 10.9 from 35 in | 62/100 · C |
| Snowfall burden | 24.5 inches/year | 44/100 · D |
| Annual temperature balance | 50.3°F · 17.2° from 67.5°F | 42/100 · D |
Chatham · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Chatham is a continental Köppen climate: Dfb
Coldest-month mean 31.7°F and warmest-month mean 69.5°F place this station in continental, no dry season, warm summer climates (Dfb). Class Dfb is the Peel et al. (2007) label for this station's monthly mean temperature and precipitation normals: continental, specifically continental, no dry season, warm summer.
- Köppen code
- Dfb
- Group
- Continental
- Warmest month
- 69.5°F
- Coldest month
- 31.7°F
Source: official public datasets monthly normals (1991–2020) at the city’s primary station. This is a station classification, not a mapped regional consensus.
National standing · heating-led station
Where Chatham sits across the climate record
Three NOAA fields for Chatham's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- 41st percentile warmth
- Mid-pack annual mean versus 6,861 station normals.
- Annual precipitation
- Top 30% wettest
- Chatham's annual total ranks in the wetter third of 6,352 measured normals.
- Seasonal temperature swing
- Narrower than 74%
- Warmest-to-coldest month gap for Chatham is compact versus 6,861 complete station-years.
How Chatham compares across U.S. station-mapped locations
Chatham's comfort score vs. all station-mapped locations
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
63 46th percentile score exceeds 46% of 6,189 station-mapped location scores
- 0–10: 0 station-mapped locations (0%). Below this entry.
- 10–20: 0 station-mapped locations (0%). Below this entry.
- 20–30: 96 station-mapped locations (2%). Below this entry.
- 30–40: 280 station-mapped locations (5%). Below this entry.
- 40–50: 1,113 station-mapped locations (18%). Below this entry.
- 50–60: 1,329 station-mapped locations (21%). Below this entry.
- 60–70: 1,236 station-mapped locations (20%). This entry sits in this band.
- 70–80: 650 station-mapped locations (11%). Above this entry.
- 80–90: 921 station-mapped locations (15%). Above this entry.
- 90–100: 564 station-mapped locations (9%). Above this entry.
Source NOAA U.S. Climate Normals, PlainClimate comfort index · 1991–2020
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Snow | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|---|
| January | 39°F (4°C) | 25°F (-4°C) | 32°F (0°C) | 4.0" | 7.5" | 23.4 | 0.0 |
| February | 39°F (4°C) | 25°F (-4°C) | 32°F (0°C) | 3.8" | 9.9" | 21.1 | 0.0 |
| March | 43°F (6°C) | 31°F (-1°C) | 37°F (3°C) | 4.7" | 3.8" | 15.9 | 0.0 |
| April | 51°F (11°C) | 40°F (4°C) | 45°F (7°C) | 4.0" | 0.5" | 2.1 | 0.0 |
| May | 60°F (15°C) | 48°F (9°C) | 54°F (12°C) | 3.3" | 0.0" | 0.0 | 0.0 |
| June | 69°F (21°C) | 57°F (14°C) | 63°F (17°C) | 3.2" | 0.0" | 0.0 | 0.1 |
| July | 76°F (24°C) | 63°F (17°C) | 70°F (21°C) | 2.8" | 0.0" | 0.0 | 0.0 |
| August | 76°F (24°C) | 63°F (17°C) | 69°F (21°C) | 3.2" | 0.0" | 0.0 | 0.0 |
| September | 70°F (21°C) | 58°F (15°C) | 64°F (18°C) | 3.8" | 0.0" | 0.0 | 0.0 |
| October | 61°F (16°C) | 49°F (9°C) | 55°F (13°C) | 4.3" | 0.0" | 0.0 | 0.0 |
| November | 52°F (11°C) | 40°F (4°C) | 46°F (8°C) | 4.1" | 0.2" | 4.8 | 0.0 |
| December | 44°F (7°C) | 31°F (0°C) | 38°F (3°C) | 4.7" | 2.6" | 15.8 | 0.0 |
The year, day by day
Summer here tops out rather than builds: the warmest normal high is 77°F around July 24, short of 90°F on every date, while 100 dates carry a normal low at or below freezing, the coldest 24°F near January 26.
The freezing stretch
The normal low stays at or below 32°F into March 21, then returns to freezing around December 13, covering 100 dates in all.
Derived from the normal daily minimum. This is a different measure from the 50%-probability frost dates shown elsewhere on this page, which come from NOAA’s frost product.
Where the wet dates fall
The likeliest wet date is December 25, when 41% of years recorded at least a hundredth of an inch. The driest is August 25 at 26%. Summed across the calendar, that is about 127 wet dates a year.
The widest day
February 5 carries the biggest normal gap between afternoon and dawn, 14°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Chatham.
Where Chatham Stands Nationally
Among the steadiest day-night climates ranked: even the widest normal daily swing holds to roughly 14°F.
Chatham earns one nationally notable standing (outer quintile) against 6,860 NOAA 1991–2020 normals stations, middle-of-the-pack metrics stay silent here.
Monthly Precipitation
Average monthly rainfall and snowfall
Snow: 7.5"
12.4 days with precipitation
Snow: 9.9"
10.9 days with precipitation
Snow: 3.8"
11.7 days with precipitation
Snow: 0.5"
11.5 days with precipitation
11.0 days with precipitation
9.6 days with precipitation
8.2 days with precipitation
8.3 days with precipitation
8.7 days with precipitation
10.8 days with precipitation
Snow: 0.2"
10.6 days with precipitation
Snow: 2.6"
12.9 days with precipitation
Chatham spreads its precipitation across the year
Neither half of the year dominates here: June through August take 20% of the annual total and December through February 27%, with neither reaching the 35% that would mark a distinct wet season. Chatham has no dry season to plan around, though it does carry a 37.8°F seasonal spread.
The gap between the wettest and driest month still matters: December averages 4.7" and July 2.8". The three wettest months together take 30% of the year, against the 25% a perfectly flat distribution would give them.
Shares are computed from this station's own 1991-2020 monthly precipitation normals. "Spread across the year" means neither the June-August nor the December-February share reaches 35%; it describes an average year, not the variability of any single one.
When it rains in Chatham, it arrives in quantity
45.9" of precipitation falls across only about 127 wet days here, averaging 0.36 inches each. Fewer days carry more water: the year's total is delivered in comparatively heavy events rather than persistent damp.
- Days with measurable precipitation
- about 127 a year, 35% of all days
- Average depth per wet day
- 0.36 inches
- Most wet days
- December, about 13
- Fewest wet days
- July, about 8
A wet day is one recording at least 0.01 inches. These are 1991-2020 normals: they describe an average year, and a per-day average is not a forecast of any individual storm.
Winter brings real snow to Chatham
Chatham averages 24.5 inches of snowfall a year, with February the snowiest month on the normals, spread across roughly 11 days that record measurable snow. That is depth accumulating on the ground, which is why it can exceed the annual precipitation figure: precipitation counts the liquid the snow melts down to, and fresh snow is mostly air.
- Annual snowfall: 24.5 inches of depth.
- Days recording measurable snow: about 11 a year.
- At a rough ten-to-one melt ratio, snow accounts for on the order of 5% of the year's precipitation.
NOAA 1991-2020 normals. The ten-to-one ratio is a convention, not a measurement: real ratios vary with temperature, so treat the share as an order of magnitude rather than an exact split.
Frost Dates & Growing Season
First Fall Freeze
November 15
50% probability date
Last Spring Freeze
April 5
50% probability date
Growing Season
224 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
5,681
Higher = more heating needed
Cooling Degree Days
369
Higher = more cooling needed
Warmest Month
July
Coldest Month
January
Nationwide similar cities
Other rankable U.S. places outside MA closest to Chatham on two NOAA annual-normal axes (mean temperature and annual precipitation). Chip rows use distinct link sets.
Closest by average temperature
Nearest out-of-state peers by annual mean temperature (50°F here).
- Bedford, IA 50°F · 0.0°F off
- Boulder, UT 50°F · 0.0°F off
- Central City, NE 50°F · 0.0°F off
- Clarinda, IA 50°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (45.9" here), excluding temperature-peer places.
- Jamestown, NY 45.9" · 0.0" off
- Chester, SC 45.9" · 0.0" off
- Claremore, OK 45.9" · 0.0" off
- Lebanon, VA 45.9" · 0.0" off
Snow and freeze rhythm
When cold and snow define Chatham
heating led · wet · mid swing
Chatham's energy balance leans toward cold weather: 5,681 annual heating degree days against 369 for cooling. Its 37.8°F seasonal range still makes the monthly rows more useful than the annual average alone.
Chatham's frost-free season lasts about 224 days, a middle-length window whose endpoints matter more than the annual average. It describes freeze probability, not year-specific planting conditions.
-
1. Chatham coldest normal
January
The monthly mean of 32°F (0°C) sits near freezing, so cold nights and above-freezing afternoons share the same month.
-
2. Chatham typical freeze period
January through December
The station reports average freezing days from January through December.
-
3. Chatham snow peak
February
Chatham averages 24.5 inches of snow a year, with February the snowiest month on the normals.
Questions about Chatham's climate
How much snow does Chatham get? ▼
How much energy does heating and cooling require in Chatham? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Chatham's primary station: CHATHAM (USC00191386). For informational purposes only.
Place identity: U.S. Census Bureau 2024 Gazetteer places. The 2024 Census Gazetteer identifies the exact name-and-state match as a census-designated place (GEOID 2512960), not an incorporated municipality. Match rule for Chatham: exact normalized name + state only, no fuzzy expansion, so nearby differently spelled facilities stay unmatched.
On this page every temperature, precipitation, and derived score for Chatham comes from its primary NOAA station record. No figure on this page is typed in by an editor - each value is rendered from NOAA 1991-2020 U.S. Climate Normals. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 1991–2020 normals.