Climate and monthly weather forecast
Chatham, MA

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The calm blue water and white sand on a typical beach in Cape Cod, with a visible path and a far view of the high Chatham Lighthouse, Massachusetts
The calm blue water and white sand on a typical beach in Cape Cod, with a visible path and a far view of the high Chatham Lighthouse, Massachusetts

The climate of Chatham

Predominantly falling under the Köppen climate classification of Cfa, the town of Chatham, Massachusetts, experiences a humid subtropical climate with no dry season. Geographically, the town is situated along the southeastern tip of Cape Cod and is therefore influenced notably by the Atlantic Ocean. The coastal climate manifests in the form of a comfortable year-round weather, frequent rainfall, and the absence of extremely high temperatures.

Throughout the year, Chatham is subjected to a range of temperatures and variations in its climatic pattern. The highest average monthly temperature reaches a maximum of 71.6°F (22°C) in the month of July, while the lowest plummets down to 31.6°F (-0.2°C) in January. Humidity levels remain fairly constant, hovering around the 74% to 85% range. The coastal town records noticeable rainfall every month, with October being the month with the highest rainfall 2.83" (72mm), contrasting with February, which records the least rainfall at 1.57" (40mm).

Snowfall, while not frequent, does occur in Chatham, specifically from January to March, and also in November. The town witnesses its maximum snowfall of 1.38" (35mm) in February. Additionally, wind speeds vary across the year with January and December experiencing the maximum average wind speed of 18mph (29km/h) and the minimum speed of 11.4mph (18.3km/h) is measured in August.

The best time to visit Chatham

Given the subtropical nature of its climate, the best time to visit Chatham is typically during the summer months from June to August. During this period, the average temperatures hover between 63°F (17.2°C) to 71.6°F (22°C) and the daylight hours extend up to 14.8 hours in a day, ensuring pleasurable weather for outdoor activities. Also, the lessened probability of rainfall during these months compared to other parts of the year, make it ideal for various recreational activities.

The worst time to visit Chatham

The period from December to February could be considered less popular for visits due to the low temperatures that range from 31.6°F (-0.2°C) to 41°F (5°C) and reduced daylight hours at 9.2 to 10.6 hours a day. These factors may restrict outdoor activities. Additionally, Chatham records its peak snowfall in inches during these months which might deter travelers seeking a milder climate.

Spring weather in Chatham

Springtime from March through May in Chatham is characterized by a moderate rise in temperatures that range between 39°F (3.9°C) to 54.3°F (12.4°C). Rainfall tends to increase as the season progresses, with May recording 1.81" (46mm) of rain. Though snow recedes after March, the weather remains cautiously cool, ideal for visitors appreciating a still-cool but gradually warming atmosphere.

Summer weather in Chatham

Summer months from June to August offer the most inviting weather for visitors to Chatham. During this period, average monthly high temperatures range from 63°F (17.2°C) to 71.6°F (22°C). This season also sees the longest daylight hours, extending up to 15.2 hours, along with bright sunshine ranging from 9.4 to 10.7 hours a day. Showers are also less frequent during the summer months, making this season perfect for outdoor activities.

Autumn weather in Chatham

Autumn in the span of September to November brings a slight drop in temperatures with an average range between 59.5°F (15.3°C) to 66.6°F (19.2°C). The average daylight hours start to decrease but remain ample, falling between 9.8 to 12.5 hours a day. Despite the lower temperature and daylight, this season is characterized by its color changing foliage, offering a beautiful landscape for visitors.

Winter weather in Chatham

The winter months from December through to February are marked by the lowest average temperatures, falling between 31.6°F (-0.2°C) to 41°F (5°C). Chatham observes its lowest daylight hours, hovering between 9.2 to 10.6 hours a day during these winter months. The chances of snow are also significant during this season, offering a very different landscape for visitors keen on experiencing a coastal winter.

Weather in January

Chatham, Massachusetts, in January experiences cold conditions with the highest temperature rising to 39°F (3.9°C) and lowest falling to 31.6°F (-0.2°C). Snow is a common spectacle during this month, with snowfall days recorded typically being around six. Weather in January »

Weather in February

In Chatham, the month of February is akin to its predecessor, falling under the grasp of winter's coldness. This month, Chatham sees a minor rise in temperature from January, with the lowest temperature recorded at 32°F (0°C). Weather in February »

Weather in March

March is yet another transition month in Chatham, with a shift from the peak of winter towards the initial whispers of spring. The environment becomes warmer, as the highest monthly temperature subtly climbs to 41°F (5°C). This month is marked by considerable rainfall, making it one of the rainiest periods of the year with 1.85" (47mm) of rainfall. Weather in March »

Weather in April

April in Chatham witnesses the onset of a wonderful spring season, with temperatures ascending, averaging approximately 46.9°F (8.3°C) as the monthly high. This month distinguishes itself from the comparatively rainier season of March, with a marginal increase in rainfall to 2.05" (52mm). Weather in April »

Weather in May

May in Chatham is a delightful month, as it transitions towards the eagerly awaited summer season. The highest point of temperature climbs to an average of 54.3°F (12.4°C), boosting the bloom of local flora and fauna. This month also signifies a slight decrease in rainfall than April, marking a shift from the showery spring to a much drier summer. Weather in May »

Weather in June

Chatham's June weather marks the onset of summer, characterized by warm temperatures and extended daylight hours. The temperature moves towards a balmy 63°F (17.2°C) as the highest average in the month underscoring the arrival of summer. Weather in June »

Weather in July

Chatham's weather in July is distinctively summery, with July standing as the hottest month of the year. The month's peak temperature emerges as 70.3°F (21.3°C), making it an ideal period for beach-goers and outdoor enthusiasts. Weather in July »

Weather in August

August in Chatham continues the summer trend set by July, with high temperatures and dry, sunny days. Temperatures range from a high of 71.6°F (22°C), the month's biggest temperature average. August is also characterized by a slight decrease in UV index from July, signaling shorter daylight hours as fall gradually starts to set in. Weather in August »

Weather in September

September in Chatham represents the transition from the hot summer season to the cooler autumn months. The temperature begins to drop, with the month's maximum temperature averaging at a cooler 66.6°F (19.2°C). September stands out with its increase in rainfall to 1.85" (47mm), reflecting the shift into the autumn season. Weather in September »

Weather in October

October in Chatham is emblematic of the full arrival of autumn, characterized by falling temperatures and vibrant fall colors. Although temperatures drop down from September, weather in October stays rather comfortable with 59.5°F (15.3°C) as the highest average. Weather in October »

Weather in November

The eleventh month, November, in Chatham is marked by a distinct chill in the air, signaling the onset of the cold season. Temperatures take a deeper dive, with the highest average monthly temperature dropping to 51.3°F (10.7°C). Weather in November »

Weather in December

Chatham's December concludes the year with the advent of winter. In this last month, temperatures plunge further with the highest average at 44.4°F (6.9°C), spelling out the arrival of the winter snowfall. The first flakes of snow begin to fall in December with an average snowfall of 0.67" (17mm) recorded for the month. Weather in December »
Updated: Aug 14, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What part of the year is the coldest in Chatham?

January and February are identified as the coldest months, with an average high-temperature of 39°F (3.9°C).

How many days does it rain?

Throughout the year, there are 142.4 rainfall days, and 22.09" (561mm) of precipitation is accumulated.

When does it snow?

January through April, November and December are months with snowfall.

How many days does it snow?

In Chatham, during the entire year, snow falls for 20.8 days and aggregates up to 4.37" (111mm) of snow.

When is the lowest UV index?

January through March, November and December, with an average maximum UV index of 2, are months with the lowest UV index.

When does it snow the most in Chatham?

February is the month with the most snowfall. Snow falls for 5 days and accumulates 1.38" (35mm) of snow.

What is the month with the coldest ocean?

The month with the coldest seawater is March, with an average ocean temperature of 39.9°F (4.4°C).

When is Daylight Saving Time (DST)?

On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts, and the time zone changes from EST to EDT. Daylight Saving Time ends Sunday, November 3. 2024, at 2:00 am, and the time zone reverts from EDT to EST.

When it does not snow?

In Chatham, snow does not fall in May through October.

What is the most humid month?

The months with the highest humidity are June and July, with an average relative humidity of 85%.

When are the longest days?

With an average of 15h and 12min of daylight, June has the longest days of the year.

What is the month with the highest UV index?

July and August, with an average maximum UV index of 6, are months with the highest UV index.

What time of the year is the hottest?

August brings the highest temperatures in Chatham, with an average high of 71.6°F (22°C) and an average low of 68.2°F (20.1°C).

What month is the ocean warmest?

The month with the warmest seawater is August, with an average ocean temperature of 67.6°F (19.8°C).

What month has the most sunshine?

The month with the most sunshine is August, with an average of 10.7h of sunshine.

What is the rainiest month?

The month with the most rainfall is October, when the rain falls for 13.4 days and typically aggregates up to 2.83" (72mm) of precipitation.

What is the least humid month?

With an average relative humidity of 74%, November is the least humid month.

What is the driest month in Chatham?

The month with the least rainfall is November, when the rain falls for 11.5 days and typically collects 1.46" (37mm) of precipitation.

What is the month with the shortest days in Chatham?

December has the shortest days of the year, with an average of 9h and 12min of daylight.

What is the month with the least sunshine?

The month with the least sunshine in Chatham is December, with an average of 4.3h of sunshine.

Average temperature
Chatham, MA

Average temperature - Chatham, MA

The warmest month (with the highest average high temperature) is August (71.6°F).
The months with the lowest average high temperature are January and February (39°F).

The month with the highest average low temperature is August (68.2°F).
The coldest month (with the lowest average low temperature) is January (31.6°F).

Average pressure
Chatham, MA

Average pressure - Chatham, MA

The month with the highest atmospheric pressure is November (30.06"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).

Average wind speed
Chatham, MA

Average wind speed - Chatham, MA

The windiest month (with the highest average wind speed) is January (18mph).
The calmest month (with the lowest average wind speed) is August (11.4mph).

Average humidity
Chatham, MA

Average humidity - Chatham, MA

The months with the highest relative humidity are June and July (85%).
The month with the lowest relative humidity is November (74%).

Average rainfall
Chatham, MA

Average rainfall - Chatham, MA

The wettest month (with the highest rainfall) is October (2.83").
The driest month (with the least rainfall) is November (1.46").

Average rainfall days
Chatham, MA

Average rainfall days - Chatham, MA

The month with the highest number of rainy days is May (14.6 days).
The month with the least rainy days is February (8.3 days).

Average snowfall
Chatham, MA

Average snowfall - Chatham, MA

The month with the highest snowfall is February (1.38").
The months with the least snowfall are May, June, July, August, September and October (0").

Average snowfall days
Chatham, MA

Average snowfall days - Chatham, MA

The month with the highest number of snowfall days is January (6 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).

Average sea temperature
Chatham, MA

Average sea temperature - Chatham, MA

The best month for swimming (with the highest average sea temperature) is August (67.6°F).
The coldest month (with the lowest average sea temperature) is March (39.8°F).

Average daylight / Average sunshine
Chatham, MA

Average daylight / Average sunshine - Chatham, MA

The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 12min).

The month with the most sunshine is August (Average sunshine: 10h and 42min).
The month with the least sunshine is December (Average sunshine: 4h and 18min).

Average sunshine days
Chatham, MA

Average sunshine days - Chatham, MA

The month with the most sunshine days is August (17.6 days).
The month with the least sunshine days is January (13 days).

Average UV index
Chatham, MA

Average UV index - Chatham, MA

The months with the highest UV index are July and August (UV index 6).
The months with the lowest UV index are January, February, March, November and December (UV index 2).

Average visibility
Chatham, MA

Average visibility - Chatham, MA

The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

Chatham, Massachusetts, USA

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