Maryland State Climatologist Office

Climatology of Extreme Temperatures and Precipitation in Maryland

This analysis identifies the climatology of extreme events in temperature and precipitation and growing degree days from daily area-averaged temperatures and precipitation from the NCEI's nClimDiv-Daily data set, v1.0.0. The analysis is done at statewide, climate division and county levels for 1) Hot Days as those whose daily maximum temperature is larger than 86°F; 2) Warm Days (summer days in the literature) as those whose daily maximum temperature is larger than 80°F; 3) Warm Nights (tropical nights in the literature) as those whose daily minimum temperature is larger than 68°F; 4) Freezing Days as those whose daily minimum temperature is qual to or smaller than 32°F; 5) Dry Spells as those whose daily accumulated precipitation is equal or lower than 0.04 inches for at least two consecutuve days; 6) Extreme Precipitation as those whose daily accumulated precipitation is equal or larger than the 95 percentily of daily precipitation in the period 1951-2000, and 7) Accumulated Growing Degree Days. If the days/nights occur for two or more consecutive days they define a Heat Wave, a Warm Day Spell, a Warm Night Spell, a Freezing Spell.

Summary tables are linked below for two periods, the current 1991-2020 climate normal, and the 1951-2000 20th Century climatology.