Frost dates for Upper Marlboro 3 NNW, Maryland
Half of years have their last spring frost by April 9, but 1 year in 10 still frosts after April 24.
A frost date is really a percentile from 30 years of records at a nearby weather station: in about half of years a frost still comes after the median date. Both numbers are below, so you can choose the risk yourself.
The odds
Last spring frost
How often a frost still comes on or after each date.
- 1 year in 10
- April 24
- 1 year in 5
- April 19
- 3 years in 10
- April 15
- 2 years in 5
- April 12
- Half of years (the median)
- April 9
First fall freeze
How often the first freeze comes on or before each date.
- 1 year in 10
- October 14
- 1 year in 5
- October 19
- 3 years in 10
- October 23
- 2 years in 5
- October 26
- Half of years (the median)
- October 29
- Growing season
- about 203 days
- Hardiness zones nearby
- 7b, 8a
- Summer days
- a usual high of about 30 °C86 °F
- Lettuce and spinach run to seed
- June to September, in hot, long days (how we know)
Summer and rain
A growing garden needs about 25 mm1 in of water a week, rain and watering together. Here is what a normal month brings.
Month by month
- January
- high ~7 °C44 °F · low ~-4 °C25 °F · rain ~75 mm3 in
- February
- high ~8 °C47 °F · low ~-3 °C26 °F · rain ~68 mm2.7 in
- March
- high ~13 °C55 °F · low ~0 °C33 °F · rain ~100 mm3.9 in
- April
- high ~19 °C67 °F · low ~6 °C44 °F · rain ~86 mm3.4 in
- May
- high ~24 °C75 °F · low ~12 °C53 °F · rain ~104 mm4.1 in
- June
- high ~29 °C83 °F · low ~17 °C63 °F · rain ~107 mm4.2 in
- July
- high ~31 °C88 °F · low ~20 °C67 °F · rain ~107 mm4.2 in
- August
- high ~30 °C86 °F · low ~18 °C65 °F · rain ~105 mm4.1 in
- September
- high ~27 °C80 °F · low ~15 °C58 °F · rain ~115 mm4.5 in
- October
- high ~20 °C69 °F · low ~8 °C46 °F · rain ~105 mm4.1 in
- November
- high ~14 °C58 °F · low ~2 °C35 °F · rain ~82 mm3.2 in
- December
- high ~9 °C48 °F · low ~-2 °C29 °F · rain ~90 mm3.6 in
Where these numbers come from
NOAA NCEI 1991–2020 Climate Normals, the Upper Marlboro 3 NNW station (listed by NOAA as Upper Marlboro 3 NNW, USC00189070), at 38.85, -76.77. These are that station’s own records, unshifted. The further your garden is from it, the less exactly they describe your ground. The planner finds the nearest station to your garden and lowers its confidence with distance, so no number is presented as if it were measured in your garden.
Cold air also pools in low ground on the clear, still nights when frost happens, so a hollow can freeze while a slope a few hundred feet away does not. No table can know that about your garden. A few seasons of your own logged frosts can.
ZIP codes nearest this station
20613, 20623, 20711, 20714, 20736, 20747, 20751, 20754, 20758, 20762, 20772, 20774…
+2 moreShow fewer
20778, 20779.
Nearby stations
The nearest stations and how their last-frost dates compare. Together they show how frost varies across your area.
- Washington Reagan Airport, VA, last frost by March 24
- Dalecarlia Rsvr, MD, last frost by April 9
- Baltimore Wash International Airport, MD, last frost by April 10
- Mechanicsville 5 NE, MD, last frost by April 17
- Vienna, VA, last frost by April 14
- Royal Oak 2 SSW, MD, last frost by April 1
Other stations in Maryland.
- Cylburn, MD, last frost by April 2
- Damascus 3 SSW, MD, last frost by April 14
- Patuxent River Naval Air Station, MD, last frost by March 29
- Millers 4 NE, MD, last frost by April 19
- Conowingo Dam, MD, last frost by April 3
- Salisbury, MD, last frost by April 3
- Hagerstown Washington County Airport, MD, last frost by April 7
- Cumberland 2, MD, last frost by April 15
When do I plant? · Where the dates come from
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