Last updated: January 18, 2025
Connecticut's climate presents a unique blend of Koppen-Geiger climate classes—primarily characterized as Dfa, Cfa, Dfb, and Cfb—which contribute to its diverse weather patterns. The state's temperature experiences notable extremes, with a minimum dipping to -24°C (-11°F) in February, while soaring to a maximum of 38°C (101°F) during the peak of July. The average temperature rests comfortably at 11°C (53°F), reflecting the region's distinct seasonal variation, influenced by both its geographical location and the interplay of contrasting air masses.
Connecticut exhibits marked seasonal temperature patterns, characterized by cold winters and warm summers. The year begins with harsh conditions in January and February, where temperatures can plummet to -24°C (-11°F) and rise only to the low twenties Fahrenheit. As spring approaches, temperatures gradually rise, with March seeing averages increase to 4°C (39°F) and April reaching between 9°C (49°F) and 30°C (86°F). By May, the region experiences a notable warming, with average temperatures around 15°C (59°F), setting the stage for hot summer months. July typically marks the peak of warmth, boasting maximums of 38°C (101°F), while August remains similarly warm. As autumn unfolds, temperatures begin to drop sharply, with November averaging just 7°C (44°F), and December returning to colder extremes, highlighting the stark contrasts that define Connecticut’s climate throughout the year.
Mystic experiences temperatures ranging from a chilly minimum of -16°C (4°F) in January to a warm maximum of 29°C (85°F) in July. In comparison, Greenwich sees colder winters and hotter summers, with temperatures plummeting to a minimum of -18°C (0°F) in January and soaring to a maximum of 35°C (96°F) in July. For more detailed information on the monthly temperature in Mystic and monthly temperature in Greenwich, you can refer to these links.
Connecticut experiences a variable precipitation pattern throughout the year, with notable peaks during the late spring and fall months. January begins the year with relatively low precipitation, averaging 73 mm (2.9 in) over approximately 8 days. As winter transitions to spring, February and March see a slight increase, with February reaching 97 mm (3.8 in) and March maintaining a similar level at 94 mm (3.7 in). However, by April, precipitation significantly rises to 131 mm (5.1 in), coinciding with the onset of spring showers, and continues to be substantial in May at 115 mm (4.5 in).
The summer months bring a peak in precipitation, particularly in July when Connecticut receives 144 mm (5.6 in), often accompanied by thunderstorms. August sees a decrease to 102 mm (4.0 in), followed by a slight uptick in September with 104 mm (4.1 in). The fall also demonstrates consistent precipitation, especially in October with 142 mm (5.6 in). Overall, the state's precipitation is well-distributed, with wettest months typically occurring in spring and fall, while the number of rainy days averages around 10 to 12 days each month, creating a dynamic and changing landscape throughout the year.
Connecticut's sunshine duration exhibits a clear seasonal trend, marked by a gradual increase from the winter months into the heart of summer. January begins with a modest 150 hours of sunshine, which slowly climbs to 183 hours in February. As spring approaches, the brightness intensifies; March witnesses a leap to 256 hours, followed by a slight dip in April to 245 hours. May brings an upswing, reaching 281 hours of sunlight, effectively heralding the arrival of warmer days. The peak months for sunshine occur in the summer, with June basking in 319 hours and July shining the brightest at 341 hours.
As summer transitions into fall, the sunshine duration remains commendable, with August still capturing 323 hours. However, the onset of autumn signals a gentle decline in sunlight, with September featuring 280 hours before a notable drop in October to 221 hours. The months of November and December are characterized by shorter days and reduced sunshine, recording 206 hours and 176 hours, respectively. This seasonal pattern not only influences daily life in Connecticut but also underscores the importance of sunlight for various activities and the natural environment across the year.
Connecticut's UV Index demonstrates a distinct seasonal fluctuation, reflecting the state's varying levels of sun exposure throughout the year. During the winter months, particularly in January and December, the UV Index remains relatively low, registering at 3 and 2, respectively. February shows a slight increase to 5, while March rises further to 6, signaling that spring is on the horizon and that sun protection becomes increasingly relevant as daylight hours extend and UV radiation begins to strengthen.
The UV Index peaks in the summer months, with May, June, July, and August all experiencing elevated levels of 10—the highest of the year. This period necessitates heightened awareness of UV exposure, especially during afternoon hours when the sun is most intense. As autumn approaches, the UV Index begins its gradual decline, with September at 8 and slipping to 6 in October. By November, it decreases to 4, underscoring the importance of adjusting sun safety practices as the year progresses and UV radiation levels fluctuate with the seasons.
UV Risk Categories
Daylight duration in Connecticut illustrates a clear seasonal progression, where daylight hours fluctuate significantly from winter to summer. In January, residents experience just 9 hours of daylight, which gradually increases to 10 hours in February as the days begin to lengthen. This trend accelerates through March, as daylight reaches 11 hours, and springs forward in April with 13 hours of sunlight. The culmination of this increase occurs in June, where Connecticut enjoys a generous 15 hours of daylight, providing ample opportunity for outdoor activities during the vibrant summer months.
As summer wanes, daylight hours begin to decline, starting with 14 hours in July and tapering off to 13 hours in August. The descent continues into September with 12 hours of daylight, falling to 11 hours in October as autumn settles in. By November, daylight shrinks back to 9 hours, mirroring the conditions in January and December. This cyclical pattern reflects the natural rhythm of the seasons, underscoring the importance of sunlight for both ecological systems and human activities throughout the year in Connecticut.
Greenwich, United States, experiences a varied climate throughout the year. Winters are typically cold with January seeing the lowest temperatures, ranging from -18°C (0°F) to 18°C (64°F), and moderate precipitation of 69 mm (2.7 in). Summer temperatures are warmer, peaking in July with highs reaching 35°C (96°F) and accompanied by the year's heaviest rainfall of 143 mm (5.6 in). The region enjoys substantial sunshine during the warmer months with July recording the longest duration at 339 hours. In contrast, winter and fall months receive less sunlight, evidenced by January's 149 hours of sunshine. For more details, visit the Greenwich climate.
Mystic, United States, experiences a diverse climate characterized by chilly winters and warm, humid summers. The temperature fluctuates significantly throughout the year, with winter lows dropping to -16°C (4°F) in January and summer highs reaching up to 29°C (85°F) in July. Precipitation is fairly distributed year-round, peaking in October at 157 mm (6.2 in), while sunshine varies with a low of 152 hours in January and a high of 351 hours in July. Mystic climate provides further details on the area's weather patterns, reflecting its coastal setting in Connecticut.
In summary, Connecticut's climate, characterized by distinct seasonal variations, significantly influences its weather patterns, temperature fluctuations, precipitation levels, UV exposure, and daylight duration throughout the year. The state endures cold winters with ample snowfall, leading to a gradual transition into warmer spring and summer months characterized by higher temperatures and increased sunshine. This seasonal transformation not only presents opportunities for outdoor activities but also necessitates awareness regarding UV exposure and temperature variations. As the year progresses, Connecticut's residents adapt to these changes, utilizing the diverse climatic conditions to engage in various cultural and recreational pursuits, all while being mindful of the environmental factors that shape their daily lives.