Galveston’s climate is classified as humid subtropical , and is part of USDA Plant hardiness zone 9b. Prevailing winds from the south and southeast bring moisture from the Gulf of Mexico. Summer temperatures regularly exceed 90 °F (32 °C) and the area’s humidity drives the heat index even higher, while nighttime lows average around 80 °F (27 °C). Winters in the area are temperate with typical January highs above 60 °F (16 °C) and lows near 50 °F (10 °C). Snowfall is generally rare; however, 15.4 in (39.1 cm) of snow fell in February 1895, making the 1894–95 winter the snowiest on record. Annual rainfall averages well over 40 inches (1,000 mm) a year with some areas typically receiving over 50 inches (1,300 mm). Temperatures reaching 20 °F (−7 °C) or 100 °F (38 °C) are quite rare, having last occurred on December 23, 1989, and June 25, 2012, respectively. Record temperatures range from 8 °F (−13 °C) on February 12, 1899, up to 104 °F (40 °C) on September 5, 2000; the record cold maximum is 25 °F (−4 °C) on February 7, 1895, and again on the date of the all-time low, while, conversely, the record warm minimum is 87 °F (31 °C) set on August 31 – September 3, 2020.
Hurricanes are an ever-present threat during the summer and fall season, which puts Galveston in Coastal Windstorm Area. Galveston Island and the Bolivar Peninsula are generally at the greatest risk among the communities near the Galveston Bay. However, though the island and peninsula provide some shielding, the bay shoreline still faces significant danger from storm surge.