Climate and monthly weather forecast
Cos Cob, CT

Today
Tomorrow
Long-term
YearJFMAMJJASOND
°Celsius°Fahrenheit
Share
Contents

The climate of Cos Cob

Geographically, Cos Cob, Connecticut, USA falls under the Köppen climate classification of Cfa, meaning it has a humid subtropical climate with no dry season. The temperate weather exhibits different atmospheric conditions varying among cold winters, mild springs, hot summers, and pleasant autumns. The given annual climatic parameters provide fascinating insights into the evolving weather conditions of this region.

The yearly temperature fluctuates between a low of 26.1°F (-3.3°C) and a high of 82°F (27.8°C), witnessing a transition from chilly winters to warm summers. Relative humidity hovers around 72% to 75%, ensuring humid weather throughout the year. Rainfall is a common phenomenon in Cos Cob, with each month receiving between 2.4" (61mm) to 4.13" (105mm), with the maximum occurrence in July. The frequency of rainy days varies from 7.9 days in January to 18.1 days in July, noting a visible shift from winter to summer.

Snowfall in Cos Cob is more of a winter specialty with January being the busiest month receiving 1.97" (50mm) and 7.2 snowfall days. The coastal location of Cos Cob influences the sea temperature, with a low of 39.5°F (4.2°C) in February and a high of 73.1°F (22.8°C) in August. The daylight hours usually range from a low of 9.3 hours to a maximum of 15.1 hours in June, and a corresponding shift in sunshine hours from 4.7 hours in February to 10.5 hours in July. Wind, a constant companion in Cos Cob, varies in speed from 7mph (11.3km/h) in July to 9.9mph (15.9km/h) in January, with the strongest gusts reaching 15mph (24.1km/h) in March.

The best time to visit Cos Cob

The sweet spot for visiting Cos Cob is arguably during late spring and early summer - between May and June. During this period, the average high temperature ranges from 66.2°F (19°C) to 74.7°F (23.7°C), complemented by long daylight hours of 14.5 to 15.1. The sea temperature also begins to warm up from 51.4°F (10.8°C) to 63°F (17.2°C), ideal for water activities. While the rainfall is moderate, the sunny days make up for it with average sunshine hours peaking from 8.7 to 9.5.

The worst time to visit Cos Cob

Winter months, specifically January and February, could be considered less ideal for visiting Cos Cob. With the recorded temperature dropping to an average low of 26.1°F (-3.3°C) in January and high of only 38.3°F (3.5°C) in February, the cold is too biting for outdoor activities. Additionally, the sea temperature drops to a chilling 39.5°F (4.2°C) in February. The daylight hours are also shorter, ranging from 9.6 to 10.7 hours, significantly shortening the time for any sightseeing venture.

Spring weather in Cos Cob

Spring in Cos Cob unfolds from March to May, which sees the weather transitioning from cold to mild. Temperatures gradually ascend from 33.8°F (1°C) to 53.1°F (11.7°C). There's an increase in rainfall with April bringing the most at 3.11" (79mm). Sunshine hours extend from 6.2 to 8.7 hours, offering longer time for outdoor pursuits.

Summer weather in Cos Cob

Summer in Cos Cob spans between June and August, marked by temperatures soaring from 61.5°F (16.4°C) to 69.1°F (20.6°C). The ample sunlight, with 15.1 daylight hours in June, along with sea temperatures reaching 73.1°F (22.8°C) in August, ensure perfect conditions for water activities. While this season receives the year's highest rainfall at 4.13" (105mm) in July, it does not deter the fun outdoor possibilities.

Autumn weather in Cos Cob

Autumn graces Cos Cob between September and November, noted by a decrease in temperature from 61.7°F (16.5°C) in September to 40.6°F (4.8°C) in November. Whilst the rainfall remains moderate, the sunshine hours gradually decrease from 8.8 hours in September to 5.6 hours in November, indicating shorter days for outdoor indulgence.

Winter weather in Cos Cob

Winter sets in Cos Cob during December, lasting until February. It features colder temperatures from 33.3°F (0.7°C) to 26.1°F (-3.3°C) along with snowfall, especially in January with 1.97" (50mm). The chilly sea temperature, minimal daylight hours ranging from 9.3 to 9.6, and the lower UV index make winters less favorable for outdoor activities.

Weather in January

In Cos Cob, the weather in January starts the year off with a mix of rain, snow and cold temperatures. It's a bit fresher compared to December, especially at night. Notably, January has less daylight hours, an average of 9.6 hours a day, with a high of 35.8°F (2.1°C) and a low of 26.1°F (-3.3°C). Weather in January »

Weather in February

As the year progresses, February marks a slight shift in the weather in Cos Cob. The temperatures are a bit milder compared to January. Notable is that despite having 10.7 daylight hours, the abundance of cloud cover keeps February comparatively chilly with a high of 38.3°F (3.5°C) and a low of 27.7°F (-2.4°C). Weather in February »

Weather in March

March in Cos Cob is the transition between winter and spring, with weather that's slightly warmer than the preceding winter months. An important aspect is that daylight hours increase to 12 hours a day. In March, the high and low temperatures average 45°F (7.2°C) and 33.8°F (1°C) respectively, suggesting an increase from February. Weather in March »

Weather in April

Cos Cob in April experiences a definitive shift towards spring. The weather is appreciably warmer than in March, with less snowfall. The high temperature rises significantly up to 55.4°F (13°C) and the low to 43.5°F (6.4°C) and daylight increases to a total of 13.3 hours, marking the transition into longer, sunnier days. Weather in April »

Weather in May

In May, the weather in Cos Cob embraces the characteristics of spring fully. Temperatures become pleasant, there's more sunshine, and the winter's snow becomes a memory. Along with a high and low temperature of 66.2°F (19°C) and 53.1°F (11.7°C) respectively, May features a rich 14.5 daylight hours, making outdoor activities highly enjoyable. Weather in May »

Weather in June

Jul marks the beginning of summer in Cos Cob. The weather is distinctively warmer than May, making ice-creams and shades a necessity. The high and low temperature in June oscillates between 74.7°F (23.7°C) and 61.5°F (16.4°C), introducing a delightful chance for beach getaways. Weather in June »

Weather in July

The weather in Cos Cob in July reaches the peak of summer. The days are hot, significantly hotter than June, becoming the perfect time for a dip in the sea. Remarkably, July records the highest highs and lows of the year, from 82°F (27.8°C) to 69.1°F (20.6°C), but with the added comfort of sea breezes. Weather in July »

Weather in August

August in Cos Cob continues the summer vibe, even though the weather is slightly cooler than July. Residents and visitors can still enjoy the beach and picnics in the park. In August, the high temperature is approximately 80.6°F (27°C), and the low is about 68.7°F (20.4°C), indicating a slight drop compared to July. Weather in August »

Weather in September

Comes September, the transition from summer to autumn brings about a change in the weather in Cos Cob. The temperatures are cooler and days shorter than August. The high and low temperatures range from 73.4°F (23°C) to 61.7°F (16.5°C), making days comfortable for outdoor activities involving the fantastic fall foliage. Weather in September »

Weather in October

In Cos Cob, October ushers in the heart of the fall season. The weather cools significantly from September and prepares for the slow approach of winter. The high and low temperatures vary from 62.4°F (16.9°C) to 51.8°F (11°C), outlining the upcoming colder days. Weather in October »

Weather in November

November in Cos Cob is the precursor to winter, with temperatures lower than October. The days become significantly shorter, and the chill deepens. The transition from 50.9°F (10.5°C) high temperature to 40.6°F (4.8°C) low indicates the oncoming winter with the increased likelihood of snowfall. Weather in November »

Weather in December

December's weather in Cos Cob, Connecticut, marks the return of the cold winter months. There is a definitive drop in temperature from November, making it the coldest month of the year. The high and low temperatures fall to a chilling 41.9°F (5.5°C) and 33.3°F (0.7°C), making layers and heaters a necessity. Weather in December »
Updated: Feb 10, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What time of the year is the coldest in Cos Cob?

The coldest temperatures in Cos Cob occur during January, when averages reach a peak of 35.8°F (2.1°C) and a low of 26.1°F (-3.3°C).

What is the driest month in Cos Cob?

January and February are months with the least rain in Cos Cob, Connecticut, when the rain falls for 7.9 days and typically aggregates up to 2.4" (61mm) of rain.

How many days does it rain in Cos Cob?

In Cos Cob, during the entire year, the rain falls for 165.6 days and collects up to 37.64" (956mm) of precipitation.

When does it snow in Cos Cob?

Months with snowfall in Cos Cob, Connecticut, are January through April, November and December.

How many days does it snow in Cos Cob?

Throughout the year, in Cos Cob, Connecticut, there are 25.5 snowfall days, and 8.78" (223mm) of snow is accumulated.

What are the months with the lowest UV index in Cos Cob?

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

What is the most humid month in Cos Cob?

February, May and December, with an average relative humidity of 75%, are most humid months in Cos Cob, Connecticut.

When does it snow the most in Cos Cob?

February is the month with the most snowfall. Snow falls for 7.1 days and accumulates 2.52" (64mm) of snow.

What month is the ocean coldest in Cos Cob?

With an average ocean temperature of 39.4°F (4.1°C), February is the month with the coldest seawater in Cos Cob.

What is the month with the least sunshine in Cos Cob?

With an average of 4.7h of sunshine, February has the least sunshine of the year.

When is Daylight Saving Time (DST) in Cos Cob?

On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts in Cos Cob, 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 Cos Cob?

May through October are months without snowfall in Cos Cob.

When are the longest days in Cos Cob?

With an average of 15h and 6min of daylight, June has the longest days of the year in Cos Cob.

What are the months with the highest UV index in Cos Cob?

June through August, with an average maximum UV index of 6, are months with the highest UV index in Cos Cob, Connecticut.

What part of the year is the hottest in Cos Cob?

July, with an average high of 82°F (27.8°C) and a low of 69.1°F (20.6°C), signifies the warmest month of the year.

What is the rainiest month in Cos Cob?

July is the month with the most rainfall. Rain falls for 18.1 days and accumulates 4.13" (105mm) of precipitation.

What month has the most sunshine in Cos Cob?

July has the most sunshine of the year in Cos Cob, Connecticut, with an average of 10.5h of sunshine.

What is the least humid month in Cos Cob?

August is the least humid month in Cos Cob, Connecticut, with an average relative humidity of 71%.

When is the ocean warmest in Cos Cob?

The month with the warmest seawater in Cos Cob is August, with an average ocean temperature of 73°F (22.8°C).

What is the month with the shortest days in Cos Cob?

With an average of 9h and 18min of daylight, December has the shortest days of the year in Cos Cob, Connecticut.
Today
Tomorrow
Long-term
YearJFMAMJJASOND

Average temperature
Cos Cob, CT

Average temperature - Cos Cob, CT

The warmest month (with the highest average high temperature) is July (82°F).
The month with the lowest average high temperature is January (35.8°F).

The month with the highest average low temperature is July (69.1°F).
The coldest month (with the lowest average low temperature) is January (26.1°F).

Average pressure
Cos Cob, CT

Average pressure - Cos Cob, CT

The month with the highest atmospheric pressure is November (30.1"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).

Average wind speed
Cos Cob, CT

Average wind speed - Cos Cob, CT

The windiest month (with the highest average wind speed) is January (9.9mph).
The calmest month (with the lowest average wind speed) is July (6.5mph).

Average humidity
Cos Cob, CT

Average humidity - Cos Cob, CT

The months with the highest relative humidity are February, May and December (75%).
The month with the lowest relative humidity is August (71%).

Average rainfall
Cos Cob, CT

Average rainfall - Cos Cob, CT

The wettest month (with the highest rainfall) is July (4.13").
The driest months (with the least rainfall) are January and February (2.4").

Average rainfall days
Cos Cob, CT

Average rainfall days - Cos Cob, CT

The month with the highest number of rainy days is July (18.1 days).
The month with the least rainy days is January (7.9 days).

Average snowfall
Cos Cob, CT

Average snowfall - Cos Cob, CT

The month with the highest snowfall is February (2.52").
The months with the least snowfall are May, June, July, August, September and October (0").

Average snowfall days
Cos Cob, CT

Average snowfall days - Cos Cob, CT

The month with the highest number of snowfall days is January (7.2 days).
The months with the least snowfall days are June, July, August, September and October (0 days).

Average sea temperature
Cos Cob, CT

Average sea temperature - Cos Cob, CT

The best month for swimming (with the highest average sea temperature) is August (73.1°F).
The coldest month (with the lowest average sea temperature) is February (39.5°F).

Average daylight / Average sunshine
Cos Cob, CT

Average daylight / Average sunshine - Cos Cob, CT

The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 18min).

The month with the most sunshine is July (Average sunshine: 10h and 30min).
The month with the least sunshine is February (Average sunshine: 4h and 42min).

Average sunshine days
Cos Cob, CT

Average sunshine days - Cos Cob, CT

The month with the most sunshine days is November (17.8 days).
The month with the least sunshine days is June (10.7 days).

Average UV index
Cos Cob, CT

Average UV index - Cos Cob, CT

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

Average cloud cover
Cos Cob, CT

Average cloud cover - Cos Cob, CT

The month with the most cloud cover is December (Cloud cover 49).
The month with the least cloud cover is August (Cloud cover 31).

Average visibility
Cos Cob, CT

Average visibility - Cos Cob, CT

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).

Cos Cob, Connecticut, USA

Weather forecast for today
Weather forecast for tomorrow
10 days weather forecast
Climate data
1January
2February
3March
4April
5May
6June
7July
8August
9September
10October
11November
12December

Weather forecast for your location

1. Click Locate me button
2. Allow the app to use your location