Climate and monthly weather forecast
Old Greenwich, CT

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The climate of Old Greenwich

Nestled in the heart of Connecticut, USA, Old Greenwich has a Humid subtropical climate, without a dry season, indicated by its Köppen climate classification of Cfa. Falling within the temperate zone, it experiences four distinct seasons. An annual overview suggests an average high temperature ranging from 36°F (2.2°C) to 81.9°F (27.7°C) and an average low varying between 26.2°F (-3.2°C) to 69.3°F (20.7°C). The coldest temperatures occur in January and February, while the warmest months typically are July and August.

Throughout the year, the relative humidity remains fairly consistent, oscillating between 71% and 75%. Rainfall is frequent in Old Greenwich, with monthly averages varying from 2.44" (62mm) to 4.13" (105mm). The most significant rainfall occurs in July, while February sees the least. Snow is predominantly a winter phenomenon, with an average snowfall ranging from 0.08" (2mm) to 2.6" (66mm) in winter months.

Sea temperatures are frequently most agreeable from June to September, rising from an average of 41.6°F (5.3°C) in January to a comfortable 73.1°F (22.8°C) in August. While daylight varies from 9.6 hours in January to 15.1 hours in June. Overall, Old Greenwich has mildly variable weather throughout the year, offering unique experiences in each season.

The best time to visit Old Greenwich

Considering the distinctive seasonal weather patterns, the best time to visit Old Greenwich largely depends on the activities one wishes to partake in. For those interested in beach activities, June to August would be ideal when the sea temperature averages between 63°F (17.2°C) and 73.1°F (22.8°C). The climate is relatively warm during these months, with an average high temperature ranging from 74.7°F (23.7°C) to 81.9°F (27.7°C).

If outdoor exploration is the key agenda, September and October offer pleasant weather, with an average high temperature from 73.2°F (22.9°C) to 62.4°F (16.9°C), and reduced rainfall as compared to the summer months. Additionally, this period benefits from comparatively lower humidity levels, offering comfortable conditions for hiking or sightseeing.

The worst time to visit Old Greenwich

Despite the charm of winter wonderlands, January and February might not be the best months to visit Old Greenwich. The temperatures during these months can drop below freezing, with an average low from 26.2°F (-3.2°C) to 27.7°F (-2.4°C). Moreover, the average snowfall in these months can reach up to 2.6" (66mm), which can cause roadblocks and hinder travel plans. This, combined with reduced daylight hours could make these months less appealing to some.

Spring weather in Old Greenwich

Spring, falling between March and May, welcomes the onset of warmer weather. Average high temperatures rise gradually from 45°F (7.2°C) to 65.8°F (18.8°C), while low temperatures hover between 34.2°F (1.2°C) and 53.2°F (11.8°C). Rainfall levels increase during this season, peaking in May with an average of 3.11" (79mm), and associated increase in humidity.

Summer weather in Old Greenwich

June through August denotes the summer season in Old Greenwich. With an average high temperature between 74.7°F (23.7°C) and 81.9°F (27.7°C), the climate is comfortably warm. Rainfall is at its peak during these months, particularly in July where it can reach 4.13" (105mm).

Autumn weather in Old Greenwich

The transition from summer to winter, the autumn season between September and November, conditions in Old Greenwich become more pleasant. With an average high temperature receding from 73.2°F (22.9°C) to 50.9°F (10.5°C) and an average low from 61.7°F (16.5°C) to 40.8°F (4.9°C), the climate is comparatively cooler. Rainfall also decreases during this period, averaging between 2.68" (68mm) and 3.46" (88mm).

Winter weather in Old Greenwich

December to February marks the winter in Old Greenwich. The average high temperature drops significantly during these months, ranging between 36°F (2.2°C) and 45°F (7.2°C). While the average low runs from 26.2°F (-3.2°C) to 34.2°F (1.2°C). Snowfall is highest in these months, reaching up to 2.6" (66mm) in January and February. Consequently, temperatures decrease to create a chilly climate, thus it would only appeal to those who appreciate colder weather.

Weather in January

In Old Greenwich, January is the month to bundle up, with temperatures dropping to the lowest degree of the year. Despite the long nights and cold weather, the heavily saturated air creates a unique aesthetic. Bitter winds blowing at 10mph (16.1km/h) can make the temperature feel even colder than it actually is. Weather in January »

Weather in February

The weather variations from January to February in Old Greenwich are minimal, with average low and high temperatures hovering around the freezing point, and rainfall amounting to 2.48" (63mm). However, the sightings of snow tend to increase, creating a lovely winter atmosphere. Weather in February »

Weather in March

As Old Greenwich moves into March, the air becomes crisper, and the days longer. The intensity of the sun's rays increases, resulting in slightly higher temperatures. The winter snow reduces gradually by this time, yet occasional flurries are not uncommon. Weather in March »

Weather in April

April weather in Old Greenwich displays the unique charm of spring, with a massive temperature rise from 45°F (7.2°C) to 55.4°F (13°C). The skies seem to cry more often with the most rainfall in months at 3.15" (80mm), nurturing the budding plants. Weather in April »

Weather in May

Old Greenwich revels in the heart of spring throughout May. The weather further warms up, and the nature bursts into a riot of colors, courtesy of the longer days and ample sunshine. Visually, it is a beautiful month as everything seems fresh and lively, becoming a favorite time for photographers and nature lovers. Weather in May »

Weather in June

June marks the onset of summer in Old Greenwich, offering long, warm days that encourage outdoor activities. The radiant sunshine and low wind speed create a perfect blend for beach-goers. While the weather remains relatively dry, occasional breeze from the seas adds a refreshing touch to the otherwise warm climate. Weather in June »

Weather in July

July, the height of summer in Old Greenwich, comes with some of the highest temperatures approaching 81.9°F (27.7°C)-and high humidity levels from 73% to 75%. Despite the heat, the city comes alive with residents flocking to beaches, thanks to the sea temperature reaching a comfortable 70.9°F (21.6°C). Weather in July »

Weather in August

The weather in August is reminiscent of July, with high temperatures lingering in Old Greenwich. The sea temperature peaks at a comfortable 73.1°F (22.8°C), continuing to draw beachgoers. An undeniable benefit of summer is the long daylight hours, which maximize outdoor activities potential. Weather in August »

Weather in September

September in Old Greenwich signals the transition from warm summer to mild fall, with temperatures beginning to decrease slowly. The rainfall is comparatively lower at 2.68" (68mm), making room for clear skies and a refreshing breeze. Weather in September »

Weather in October

October takes Old Greenwich through the heart of fall, with noticeable changes in temperature and foliage. The cooler climate encourages residents to embrace the warmth of indoor activities, although the daylight hours remain ample for enjoying the increasingly colorful outdoors. Weather in October »

Weather in November

As November rolls in, Old Greenwich begins to brace itself for the nearing winter. A significant drop in temperature, leading to a chilling low of 40.8°F (4.9°C), is a standard characteristic of Old Greenwich's November climate. Weather in November »

Weather in December

Old Greenwich, in December, witnesses the return of winter, and with it colder temperatures and short days. By now, the impressive fall foliage has given way to a more monochromatic winter scene. Even though the temperatures continue to drop, the climate remains lively leading up to the winter holidays. Weather in December »
Updated: Jul 19, 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 Old Greenwich?

January, noted for its average high-temperature of 36°F (2.2°C) and an average low-temperature of 26.2°F (-3.2°C), is considered the coldest month.

What is the driest month?

January is the month with the least rainfall. Rain falls for 8.6 days and accumulates 2.44" (62mm) of precipitation.

How much does it rain?

Throughout the year, in Old Greenwich, there are 166.6 rainfall days, and 38.07" (967mm) of precipitation is accumulated.

When does it snow in Old Greenwich?

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

How much does it snow?

In Old Greenwich, during the entire year, snow falls for 24.8 days and aggregates up to 9.33" (237mm) of snow.

What is the month with 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.

What is the most humid month?

February, May, June and December, with an average relative humidity of 75%, are most humid months.

When does it snow the most?

The month with the most snowfall is February, when snow falls for 7.3 days and typically aggregates up to 2.6" (66mm) of snow.

What month is the ocean coldest?

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

What are the months with the least sunshine?

February and December, with an average of 4.7h of sunshine, are months with the least sunshine in Old Greenwich.

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?

May through October are months without snowfall.

When are the longest days?

The month with the longest days in Old Greenwich is June, with an average of 15h and 6min of daylight.

What is the month with the highest UV index in Old Greenwich?

The months with the highest UV index are June through August, with an average maximum UV index of 6.

What part of the year is the hottest?

July registers as the month with the average highest temperatures, reaching 81.9°F (27.7°C) at its peak and 69.3°F (20.7°C) at the lowest.

What is the rainiest month?

The month with the most rainfall is July, when the rain falls for 17.8 days and typically aggregates up to 4.13" (105mm) of precipitation.

What month has the most sunshine?

With an average of 10.5h of sunshine, July has the most sunshine of the year in Old Greenwich.

What is the least humid month?

With an average relative humidity of 71%, August is the least humid month in Old Greenwich.

What is the month with the warmest ocean?

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

What is the month with the shortest days in Old Greenwich?

December has the shortest days of the year, with an average of 9h and 18min of daylight.

Average temperature
Old Greenwich, CT

Average temperature - Old Greenwich, CT

The warmest month (with the highest average high temperature) is July (81.9°F).
The month with the lowest average high temperature is January (36°F).

The month with the highest average low temperature is July (69.3°F).
The coldest month (with the lowest average low temperature) is January (26.2°F).

Average pressure
Old Greenwich, CT

Average pressure - Old Greenwich, CT

The month with the highest atmospheric pressure is November (30.09"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).

Average wind speed
Old Greenwich, CT

Average wind speed - Old Greenwich, CT

The windiest month (with the highest average wind speed) is January (10.1mph).
The calmest month (with the lowest average wind speed) is July (6.6mph).

Average humidity
Old Greenwich, CT

Average humidity - Old Greenwich, CT

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

Average rainfall
Old Greenwich, CT

Average rainfall - Old Greenwich, CT

The wettest month (with the highest rainfall) is July (4.13").
The driest month (with the least rainfall) is January (2.44").

Average rainfall days
Old Greenwich, CT

Average rainfall days - Old Greenwich, CT

The month with the highest number of rainy days is July (17.8 days).
The month with the least rainy days is January (8.6 days).

Average snowfall
Old Greenwich, CT

Average snowfall - Old Greenwich, CT

The month with the highest snowfall is February (2.6").
The months with the least snowfall are May, June, July, August, September and October (0").

Average snowfall days
Old Greenwich, CT

Average snowfall days - Old Greenwich, CT

The month with the highest number of snowfall days is February (7.3 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).

Average sea temperature
Old Greenwich, CT

Average sea temperature - Old Greenwich, 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
Old Greenwich, CT

Average daylight / Average sunshine - Old Greenwich, 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 months with the least sunshine are February and December (Average sunshine: 4h and 42min).

Average sunshine days
Old Greenwich, CT

Average sunshine days - Old Greenwich, CT

The month with the most sunshine days is November (17.9 days).
The month with the least sunshine days is June (11.1 days).

Average UV index
Old Greenwich, CT

Average UV index - Old Greenwich, 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 visibility
Old Greenwich, CT

Average visibility - Old Greenwich, 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).

Old Greenwich, Connecticut, USA

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