Hartford lies in the humid continental climate zone . Winters are cold, with periods of snow, while summers are warm to hot and humid. Spring and fall are normally transition seasons, with weather ranging from mild to cool. The city of Hartford lies in USDA Hardiness zone 6a.
Seasonally, the period from May through October is warm to hot in Hartford, with the hottest months being June, July, and August. In the summer months there is often high humidity and occasional (but brief) thundershowers. The cool to cold months are from November through April, with the coldest months in December, January, and February having average highs 35 °F (2 °C) to 38 °F ( 1 °C to 3 °C) and overnight lows around 18 °F (−8 °C) to 23 °F (−8 °C to −5 °C).
The average annual precipitation is approximately 45.9 inches (1,170 mm), which is distributed fairly evenly throughout the year. Hartford typically receives about 44.5 inches (113 cm) of snow in an average winter – about 40% more than coastal Connecticut cities like New Haven, Stamford, and New London. Seasonal snowfall has ranged from 115.2 inches (293 cm) during the winter of 1995–96 to 13.5 inches (34 cm) in 1999–2000. During the summer, temperatures reach or exceed 90 °F (32 °C) on an average of 17 days per year, in the winter, overnight temperatures can dip to 5 to −5 °F (−15 to −21 °C) at least one night a year. Tropical storms and hurricanes have also struck Hartford, although the occurrence of such systems is rare and is usually confined to the remnants of such storms. Hartford saw extensive damage from the 1938 New England Hurricane, as well as with Hurricane Irene in 2011. The highest officially recorded temperature is 103 °F (39 °C) on July 22, 2011 and the lowest is −26 °F (−32 °C) on January 22, 1961; the record cold daily maximum is −2 °F (−19 °C) on December 2, 1917, while, conversely, the record warm daily minimum is 80 °F (27 °C) on July 31, 1917.