Climate and monthly weather forecast
Connecticut, USA

Connecticut climate ranges from humid continental type (Köppen climate classification Dfa, Dfb) in the north to humid subtropical (Köppen Cfa, Cfb) in the south. Summers are hot and humid, while winters range from mild on the coast to cold and snowy in the interior. Connecticut lies in the southwestern New England region, which is the northeastern part of the United States. Rhode Island in the east, Long Island Sound in the south, New York in the west, and Massachusetts in the north border the state. The climate varies by region, and there is little influence of geographical factors other than the water bodies in the south.

Connecticut, the Constitution State, has an average elevation of 150 meters above sea level with the highest point at 725 meters on the south slope of Mount Frissell on the border. The Connecticut River nearly bisects the state before flowing into the Long Island Sound in the south. The diverse topography consists of rolling hills and farms in the north to coastal marshes and beaches in the east. Northern hardwood, conifers, oak, spruce, and maple form the majority of the forests in the state. New England-Acadian forests are rife in the northwest, while northeastern coastal forests constitute parts of the south and east.

The best time to visit Connecticut is from mid-May to mid-October that encompasses the period of late spring to mid-autumn. Late spring has warm temperatures with day temperatures in the 65°F (18.3°C) to 70°F (21.1°C) range. May is warm with unexpected rain as well as bright sunshine. Summers are hot and humid but rarely go past 100°F (37.8°C). The fall season has pleasant temperatures from September to early November. The peak foliage displays in the mid of October with spectacular hues in the high country. Summer crowds disperse by the beginning of September, but there are many visitors in the fall season.

The worst time to visit Connecticut is during the winter season from December to February when the cold is at its peak. Cold fronts from the Canadian North frequently invade the state with night temperatures often dropping below 0°F (-17.8°C). Snowfall is heavy in the winter and
blizzards add to the snow depth. Wintry conditions make roads slippery with the frequent invasion of black ice. Heavy fog descends in the coastal regions during late winter. The cold season sees low footfall in Connecticut except those of snow lovers.

Spring in Connecticut transitions from slightly cool to warm, with heat increasing later in the season. Average high temperatures can reach 85°F (29.4°C) in the later parts, and thunderstorms become frequent. The state might experience an occasional tornado during the storm season. Humidity is generally at its lowest in spring, and the rainfall remains fairly even.

Summer brings hot and humid conditions to Connecticut, driven by the Bermuda High from May to July. Temperatures often register at an average high of 85°F (29.4°C), but occasional heat waves may push them above 100°F (37.8°C). Thunderstorms accompanied by lightning and thunder are common in late spring and summer. Despite this, hurricanes rarely hit the state directly, and humidity peaks in late summer.

Connecticut's autumn is mild to cold, with colorful foliage quickly progressing from north to south. Rainfall continues to be fairly even, but the sunshine becomes less prevalent compared to summer. Annual sunshine ranges from 45% to 65%, with clear days numbering from 100 to 125. Fall sees a decline in the humidity, making the weather more comfortable for outdoor activities.

Winter in Connecticut is characterized by cold temperatures, with average lows ranging from 1°F (-17.2°C) to 3°F (-16.1°C) in January. Snowfall varies significantly across the state, with southern and eastern regions receiving 20" (508mm) annually, while northern hilly areas see up to 60" (1524mm). Unusually cold winters can lead to snowfall exceeding 150" (3810mm) in higher elevations. Wintry conditions can lead to slippery roads, frequent black ice, and heavy fog in coastal regions during late winter.

January is typically the coldest month in Connecticut, characterized by freezing temperatures and significant snowfall, especially in the northern hilly regions. During this month, average low temperatures range from 1°F (-17.2°C) to 3°F (-16.1°C), making it considerably colder compared to the preceding December and subsequent February. Weather in January »

February continues the cold trend in Connecticut but generally shows a slight easing in temperatures compared to the harsher conditions of January. Average low temperatures remain in the freezing range but tend to be marginally milder, creating a transition toward the forthcoming spring months. Snowfall remains significant, particularly in the northern hilly regions. Weather in February »

March marks a transition period in Connecticut's weather, moving from the chilling grasp of winter toward the more temperate conditions of spring. Average temperatures begin to rise, though they still reflect the coolness associated with the tail end of the winter season. Snowfall becomes less common as the month progresses, especially in the southern and coastal regions. Weather in March »

April in Connecticut signifies a more definitive arrival of spring, with temperatures climbing to more comfortable levels. The northern parts of the state continue to experience slightly cooler temperatures, whereas coastal regions often enjoy more moderate warmth. Snowfall becomes a rarity during this month, confined to higher elevations and the occasional late-season storm in northern areas. Weather in April »

May ushers in warmer and more consistent spring weather in Connecticut. With the winter months firmly in the past, temperatures continue to rise, and the state begins to experience the effects of the Bermuda High, which brings hot weather conditions. Average high temperatures become pleasantly warm, reflecting the continued progression toward summer. Weather in May »

June marks the beginning of summer in Connecticut, with temperatures climbing and the state experiencing the full effect of the Bermuda High. The weather becomes hot, and the sun shines for longer durations, contributing to an average annual sunshine of 2500 hours. Average high temperatures reach 85°F (29.4°C), especially in southern and coastal areas. Weather in June »

July in Connecticut is characterized by hot and humid weather, representing the peak of the summer season. It is during this month that the highest temperatures are typically registered, with average high temperatures reaching up to 85°F (29.4°C) across the state. Heatwaves are not uncommon, and temperatures may occasionally surpass 100°F (37.8°C), particularly in southern and coastal regions. Weather in July »

August continues the summer trend in Connecticut, maintaining hot and humid conditions, but it often begins to signal a gradual transition toward the milder weather of fall. The influence of the Bermuda High persists, though it may start to wane toward the end of the month. Average high temperatures remain around 85°F (29.4°C), though occasional heatwaves can still push temperatures higher. Weather in August »

September in Connecticut marks the beginning of the fall season, with noticeable changes in temperature and a reduction in humidity. The hot summer weather begins to give way to milder conditions, though the transition can vary throughout the state. Average high temperatures decrease to the range of 65°F (18.3°C) to 70°F (21.1°C), especially in northern and inland areas. Weather in September »

October brings further transition into the fall season in Connecticut, showcasing colorful foliage and increasingly cooler temperatures. The month is often associated with pleasant weather, characterized by a crispness in the air that embodies the essence of autumn in New England. Average daytime temperatures continue to drop, often ranging from 50°F (10°C) to 60°F (15.6°C), with cooler nights. Weather in October »

November in Connecticut marks a significant transition toward the winter season. The colorful foliage of October gives way to bare trees, and the temperatures continue to decline, ushering in a cooler and more somber weather pattern. Average high temperatures drop to between 40°F (4.4°C) and 50°F (10°C), with inland and northern regions often experiencing the cooler end of this range. Weather in November »

December in Connecticut signifies the full onset of the winter season, bringing colder temperatures, increased cloud cover, and the potential for substantial snowfall. The landscape transforms, with bare trees and often snow-covered grounds replacing the colorful foliage of autumn. Average high temperatures continue their decline, ranging from 30°F (-1.1°C) to 40°F (4.4°C) (−34°F (1.1°C) to 39.9°F (4.4°C)). Weather in December »