Frost dates for Patuxent River Naval Air Station, Maryland
Half of years have their last spring frost by March 29, but 1 year in 10 still frosts after April 10.
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 10
- 1 year in 5
- April 5
- 3 years in 10
- April 3
- 2 years in 5
- April 1
- Half of years (the median)
- March 29
First fall freeze
How often the first freeze comes on or before each date.
- 1 year in 10
- November 1
- 1 year in 5
- November 5
- 3 years in 10
- November 8
- 2 years in 5
- November 12
- Half of years (the median)
- November 15
- Growing season
- about 230 days
- Hardiness zones nearby
- 7b, 8a
- Summer days
- a usual high of about 30 °C85 °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 °C45 °F · low ~-1 °C29 °F · rain ~74 mm2.9 in
- February
- high ~9 °C47 °F · low ~-1 °C31 °F · rain ~72 mm2.8 in
- March
- high ~13 °C55 °F · low ~3 °C37 °F · rain ~102 mm4 in
- April
- high ~19 °C66 °F · low ~8 °C47 °F · rain ~94 mm3.7 in
- May
- high ~24 °C75 °F · low ~14 °C57 °F · rain ~93 mm3.7 in
- June
- high ~28 °C83 °F · low ~19 °C66 °F · rain ~108 mm4.3 in
- July
- high ~31 °C87 °F · low ~22 °C71 °F · rain ~114 mm4.5 in
- August
- high ~30 °C85 °F · low ~21 °C69 °F · rain ~118 mm4.7 in
- September
- high ~26 °C79 °F · low ~17 °C63 °F · rain ~105 mm4.1 in
- October
- high ~21 °C69 °F · low ~11 °C52 °F · rain ~102 mm4 in
- November
- high ~15 °C58 °F · low ~5 °C41 °F · rain ~78 mm3.1 in
- December
- high ~10 °C50 °F · low ~1 °C34 °F · rain ~90 mm3.5 in
Where these numbers come from
NOAA NCEI 1991–2020 Climate Normals, the Patuxent River Naval Air Station station (listed by NOAA as Patuxent River Nas, USW00013721), at 38.30, -76.42. 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
20615, 20619, 20620, 20629, 20634, 20636, 20650, 20653, 20657, 20670, 20685, 20688…
+7 moreShow fewer
21622, 21626, 21627, 21634, 21669, 21672, 21675.
Nearby stations
The nearest stations and how their last-frost dates compare. Together they show how frost varies across your area.
- Mechanicsville 5 NE, MD, last frost by April 17
- Royal Oak 2 SSW, MD, last frost by April 1
- Upper Marlboro 3 NNW, MD, last frost by April 9
- Salisbury, MD, last frost by April 3
- Washington Reagan Airport, VA, last frost by March 24
- Corbin, VA, last frost by April 14
Other stations in Maryland.
- Dalecarlia Rsvr, MD, last frost by April 9
- Baltimore Wash International Airport, MD, last frost by April 10
- Cylburn, MD, last frost by April 2
- Damascus 3 SSW, MD, last frost by April 14
- Conowingo Dam, MD, last frost by April 3
- Millers 4 NE, MD, last frost by April 19
- 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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