Scattered frost has now been observed in some areas of the Commonwealth, but not enough yet to end the mosquito season. Please be aware that risk from mosquito-borne diseases will be present until we receive a hard frost and freezing temperatures predominates throughout the region.
October 18, 2018
A light frost occurs when the nighttime temperature drops to below 32 degrees Fahrenheit (0°C), and refers to the conditions that allow a layer of ice crystals to form when water vapor condenses and freezes without first becoming dew.
A hard freeze (or hard frost) is a period of at least four consecutive hours of air temperatures that are below 25 degrees Fahrenheit (-4°C). Many plants (and mosquitoes) can survive a brief frost, but very few can survive a hard freeze (from https://www.almanac.com/blog/almanac/musings/how-predict-frost)