Upper Marlboro, MD 20711 Frost Dates
Upper Marlboro, MD: when does the frost end?
Around 04/09 is the usual last spring frost, about 224 days away. Fall's first freeze usually shows up around 10/29, roughly 203 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Upper Marlboro in Zone 7b (5 to 10°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
With roughly 9 weeks until Upper Marlboro's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
The actual range around Upper Marlboro's last frost
04/09 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 03/27 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 04/24 and only about 1 year in 10 sees frost after that.
Upper Marlboro against the rest of the dataset
Upper Marlboro's growing season runs about 203 days, ranking 17,005 of 40,283 US ZIP codes measured here, longest to shortest. Within MD, it ranks 411 of 583.
Learn more
Before leaning on 20711's figures: zone vs. frost date explains why Zone 7b and Upper Marlboro's frost date answer different questions, while the frost range explains how to read the range around Upper Marlboro's dates instead of trusting one.