Frost dates for Baltimore Wash International Airport, Maryland
Half of years have their last spring frost by April 10, but 1 year in 10 still frosts after April 25.
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 25
- 1 year in 5
- April 19
- 3 years in 10
- April 16
- 2 years in 5
- April 13
- Half of years (the median)
- April 10
First fall freeze
How often the first freeze comes on or before each date.
- 1 year in 10
- October 17
- 1 year in 5
- October 22
- 3 years in 10
- October 26
- 2 years in 5
- October 29
- Half of years (the median)
- October 31
- Growing season
- about 204 days
- Hardiness zones nearby
- 7b, 8a
- Summer days
- a usual high of about 30 °C87 °F
- Lettuce and spinach run to seed
- May 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 ~6 °C43 °F · low ~-4 °C25 °F · rain ~78 mm3.1 in
- February
- high ~8 °C46 °F · low ~-3 °C27 °F · rain ~74 mm2.9 in
- March
- high ~13 °C55 °F · low ~1 °C34 °F · rain ~102 mm4 in
- April
- high ~19 °C67 °F · low ~6 °C44 °F · rain ~86 mm3.4 in
- May
- high ~24 °C76 °F · low ~12 °C53 °F · rain ~98 mm3.9 in
- June
- high ~29 °C84 °F · low ~17 °C63 °F · rain ~101 mm4 in
- July
- high ~32 °C89 °F · low ~20 °C68 °F · rain ~114 mm4.5 in
- August
- high ~30 °C87 °F · low ~19 °C66 °F · rain ~104 mm4.1 in
- September
- high ~26 °C80 °F · low ~15 °C59 °F · rain ~113 mm4.4 in
- October
- high ~20 °C68 °F · low ~8 °C47 °F · rain ~100 mm3.9 in
- November
- high ~14 °C57 °F · low ~2 °C36 °F · rain ~80 mm3.1 in
- December
- high ~9 °C47 °F · low ~-1 °C30 °F · rain ~94 mm3.7 in
Where these numbers come from
NOAA NCEI 1991–2020 Climate Normals, the Baltimore Wash International Airport station (listed by NOAA as Baltimore Wash Intl Ap, USW00093721), at 39.17, -76.68. 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
20701, 20755, 20794, 21043, 21045, 21060, 21061, 21075, 21076, 21077, 21090, 21108…
+2 moreShow fewer
21144, 21240.
Nearby stations
The nearest stations and how their last-frost dates compare. Together they show how frost varies across your area.
- Cylburn, MD, last frost by April 2
- Upper Marlboro 3 NNW, MD, last frost by April 9
- Dalecarlia Rsvr, MD, last frost by April 9
- Washington Reagan Airport, VA, last frost by March 24
- Damascus 3 SSW, MD, last frost by April 14
- Vienna, VA, last frost by April 14
Other stations in Maryland.
- Millers 4 NE, MD, last frost by April 19
- Royal Oak 2 SSW, MD, last frost by April 1
- Conowingo Dam, MD, last frost by April 3
- Mechanicsville 5 NE, MD, last frost by April 17
- Patuxent River Naval Air Station, MD, last frost by March 29
- Hagerstown Washington County Airport, MD, last frost by April 7
- Salisbury, MD, last frost by April 3
- Cumberland 2, MD, last frost by April 15
When do I plant? · Where the dates come from
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