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Gaithersburg, Maryland climate

Cfa Humid subtropical

Gaithersburg has a seasonal mild-temperate climate (Humid subtropical, Köppen Cfa). The hottest month is July with an average daily high near 87°F, while the coldest is January averaging around 27°F at night. Precipitation is fairly even year-round, totalling about 41 inches.

☀️ Summers

Hot

Highs near 87°F in July.

About 21 days a year above 90 °F

❄️ Winters

Cold

Lows near 27°F in January.

About 84 freezing nights a year

🌧️ Rain

Wet

About 41 in of rain a year.

Wettest in September

⛅ Sky & trend

Partly cloudy

A roughly even mix of sun and cloud.

+1.3 °F vs 50 years ago

Temperature & precipitation

Daily high–low temperature range with the monthly average, plus monthly precipitation · 1991–2020 normals · hover a month for the exact figures

Clear vs cloudy days

Share of days each month that are clear, partly cloudy or cloudy · 1991–2020 · hover a month for the day counts

Gaithersburg climate normals (1991–2020)

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°F)	42	45	54	66	74	82	87	85	78	66	56	46
Avg temp (°F)	35	37	45	56	65	73	78	76	69	57	47	39
Avg low (°F)	27	28	36	46	55	64	69	67	60	48	38	31
Precipitation (in)	3.1	2.6	3.7	3.2	3.6	4.0	4.0	3.1	4.0	3.5	3.3	3.4

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Avg high (°F)	42	45	54	66	74	82
Avg temp (°F)	35	37	45	56	65	73
Avg low (°F)	27	28	36	46	55	64
Precipitation (in)	3.1	2.6	3.7	3.2	3.6	4.0

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°F)	87	85	78	66	56	46
Avg temp (°F)	78	76	69	57	47	39
Avg low (°F)	69	67	60	48	38	31
Precipitation (in)	4.0	3.1	4.0	3.5	3.3	3.4

How often — frequency of weather events

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Days with measurable rain (days)	10	8	11	10	11	10	9	6	9	8	8	9
Days with high ≥ 90°F (days)	—	—	—	0.2	2	4	9	5	0.8	—	—	—
Days with low ≤ 32°F (days)	22	20	13	2	0.1	—	—	—	—	0.4	8	19
Days with snowfall ≥ 1 in (days)	2	2	0.8	—	—	—	—	—	—	—	0.2	0.5

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Days with measurable rain (days)	10	8	11	10	11	10
Days with high ≥ 90°F (days)	—	—	—	0.2	2	4
Days with low ≤ 32°F (days)	22	20	13	2	0.1	—
Days with snowfall ≥ 1 in (days)	2	2	0.8	—	—	—

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Days with measurable rain (days)	9	6	9	8	8	9
Days with high ≥ 90°F (days)	9	5	0.8	—	—	—
Days with low ≤ 32°F (days)	—	—	—	0.4	8	19
Days with snowfall ≥ 1 in (days)	—	—	—	—	0.2	0.5

Sky & atmosphere

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Cloud cover (%)	65	65	64	65	64	59	56	55	55	54	61	65
Clear days (≤ 30% cloud)	4	4	5	6	6	5	7	8	8	9	6	5
Partly cloudy days (30–70%)	11	9	10	9	10	12	12	12	10	10	10	11
Cloudy days (≥ 70%)	15	15	15	16	15	12	12	11	12	12	14	15
Relative humidity (%)	83	81	79	77	77	74	68	69	71	75	78	83
Wind speed (mph)	7.1	7.2	7.3	6.7	5.5	4.9	4.5	4.5	5.3	5.8	6.2	6.4

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Cloud cover (%)	65	65	64	65	64	59
Clear days (≤ 30% cloud)	4	4	5	6	6	5
Partly cloudy days (30–70%)	11	9	10	9	10	12
Cloudy days (≥ 70%)	15	15	15	16	15	12
Relative humidity (%)	83	81	79	77	77	74
Wind speed (mph)	7.1	7.2	7.3	6.7	5.5	4.9

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Cloud cover (%)	56	55	55	54	61	65
Clear days (≤ 30% cloud)	7	8	8	9	6	5
Partly cloudy days (30–70%)	12	12	10	10	10	11
Cloudy days (≥ 70%)	12	11	12	12	14	15
Relative humidity (%)	68	69	71	75	78	83
Wind speed (mph)	4.5	4.5	5.3	5.8	6.2	6.4

Methodology & sources

Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Rockville 1 NE (NOAA GHCN station USC00187705), about 7 km from the city centre.

Cloud, humidity, wind & sunshine — modelled estimates from NASA POWER, NASA's satellite-and-reanalysis climatology. This is the standard global source for atmospheric variables, which are not measured at most weather stations.

How we build these numbers →