Baltimore, Maryland, United States

Frost dates for Baltimore

The full distribution rather than a single date. Every figure below is a percentile of 30 years of daily minimum temperatures at this location, expressed as the date it fell on.

Median last spring frost

12 April

Half of years are later than this. Not a planting date.

Median first autumn frost

4 November

The far end of the outdoor season.

Frost-free season

206 days

Between those two dates in a median year.

Last and first frost by severity

Read a row as: in this fraction of years, the last frost of spring had already happened by this date. The 90% column is the cautious planting date; the 10% column is the gamble.

Light frost — nights at or below 0°C (32°F). Air temperature reaches freezing. Kills basil, beans and unhardened tomatoes; hardy crops shrug it off.
Frost	1 year in 10	Median	9 years in 10	Earliest	Latest
Last of spring	30 Mar	12 Apr	21 Apr	27 Mar	11 May
First of autumn	23 Oct	4 Nov	14 Nov	14 Oct	19 Nov
Frost-free days	229	206	185	every year on record saw this

Moderate frost — nights at or below -2.2°C (28°F). Damages half-hardy plants and most blossom. This is the threshold that decides a fruit crop.
Frost	1 year in 10	Median	9 years in 10	Earliest	Latest
Last of spring	23 Mar	31 Mar	9 Apr	20 Mar	17 Apr
First of autumn	4 Nov	12 Nov	25 Nov	30 Oct	1 Dec
Frost-free days	247	227	209	every year on record saw this

Hard frost — nights at or below -4.4°C (24.1°F). Ground freezes and even hardy crops check their growth. Effectively the end of the outdoor year.
Frost	1 year in 10	Median	9 years in 10	Earliest	Latest
Last of spring	2 Mar	22 Mar	4 Apr	13 Feb	11 Apr
First of autumn	15 Nov	28 Nov	17 Dec	9 Nov	25 Dec
Frost-free days	290	252	225	every year on record saw this

Dates in the southern hemisphere are computed on a growing year that starts in July, which is why "last of spring" falls where it should rather than in the middle of the calendar.

Chance of frost, week by week

Chance of at least one air frost during each week of the year, measured across the full record. The flat stretch in the middle is your frost-free season.

Temperature through the year

Mean monthly temperature across the record. Months shown in blue average at least one air frost.

Monthly means and average number of frost nights.
Month	Mean low	Mean high	Frost nights
January	-4.7°C	3.3°C	26.3
February	-4°C	5.1°C	23.6
March	-0.2°C	10.3°C	17.7
April	5.1°C	16.8°C	3.5
May	11.1°C	21.9°C	0.1
June	16.4°C	27.1°C	0
July	19.5°C	30.3°C	0
August	18.9°C	29.7°C	0
September	14.8°C	25.9°C	0
October	8.1°C	19°C	0.4
November	1.9°C	11.8°C	11.2
December	-2.3°C	5.8°C	22.8

Turn these dates into a planting calendar →

Nearby

Compare with places close by

Washington Zone 7b 57 km Last frost 3 Apr First 10 Nov Arlington Zone 7b 62 km Last frost 3 Apr First 10 Nov Alexandria Zone 7b 66 km Last frost 3 Apr First 10 Nov Philadelphia Zone 7a 144 km Last frost 14 Apr First 2 Nov Richmond Zone 8a 207 km Last frost 29 Mar First 5 Nov