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Clayton, Delaware climate

Cfa Humid subtropical

Clayton has a seasonal mild-temperate climate (Humid subtropical, Köppen Cfa). The hottest month is July with an average daily high near 31°C, while the coldest is January averaging around −2°C at night. Precipitation is fairly even year-round, totalling about 1209 mm. Light snow accumulates each winter (34 cm of snow per year on average).

☀️ Summers

Warm

Highs near 31°C in July.

About 24 days a year above 32 °C

❄️ Winters

Cold

Lows near −2°C in January.

About 77 freezing nights a year

🌧️ Rain & snow

Wet

About 1209 mm of rain a year, plus 34 cm of snow.

Snow falls through the winter months

⛅ Sky & trend

Partly cloudy

A roughly even mix of sun and cloud.

+0.3 °C vs 50 years ago

Temperature & precipitation

Daily high–low temperature range with the monthly average, plus monthly precipitation split into rain and snow · 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

Clayton climate normals (1991–2020)

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°C)	7	9	13	19	24	28	31	30	26	21	14	9
Avg temp (°C)	2	3	7	13	18	23	26	25	21	15	9	5
Avg low (°C)	−2	−2	2	7	12	18	21	20	16	10	4	0
Precipitation (mm)	87	78	107	94	99	116	105	125	108	103	85	101
Snowfall (cm)	10	15	2	—	—	—	—	—	—	—	—	7

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Avg high (°C)	7	9	13	19	24	28
Avg temp (°C)	2	3	7	13	18	23
Avg low (°C)	−2	−2	2	7	12	18
Precipitation (mm)	87	78	107	94	99	116
Snowfall (cm)	10	15	2	—	—	—

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°C)	31	30	26	21	14	9
Avg temp (°C)	26	25	21	15	9	5
Avg low (°C)	21	20	16	10	4	0
Precipitation (mm)	105	125	108	103	85	101
Snowfall (cm)	—	—	—	—	—	7

How often — frequency of weather events

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Days with measurable rain (days)	9	9	9	10	10	9	9	8	8	8	7	10
Days with high ≥ 32°C (days)	—	—	—	0.1	1	5	10	6	2	0.0	—	—
Days with low ≤ 0°C (days)	21	18	12	1	—	—	—	—	—	0.4	7	17
Days with snowfall ≥ 2.5 cm (days)	1	1	0.4	—	—	—	—	—	—	—	—	0.5

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Days with measurable rain (days)	9	9	9	10	10	9
Days with high ≥ 32°C (days)	—	—	—	0.1	1	5
Days with low ≤ 0°C (days)	21	18	12	1	—	—
Days with snowfall ≥ 2.5 cm (days)	1	1	0.4	—	—	—

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Days with measurable rain (days)	9	8	8	8	7	10
Days with high ≥ 32°C (days)	10	6	2	0.0	—	—
Days with low ≤ 0°C (days)	—	—	—	0.4	7	17
Days with snowfall ≥ 2.5 cm (days)	—	—	—	—	—	0.5

Sky & atmosphere

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Cloud cover (%)	62	62	62	62	62	59	55	54	54	54	59	63
Clear days (≤ 30% cloud)	5	5	6	6	5	6	7	8	9	10	7	5
Partly cloudy days (30–70%)	11	10	11	9	12	12	13	12	10	10	11	11
Cloudy days (≥ 70%)	14	13	15	15	14	12	11	11	11	12	12	15
Relative humidity (%)	83	82	80	78	78	76	72	73	75	77	79	83
Wind speed (mph)	7.9	7.9	8.1	7.7	6.4	5.7	5.2	5.1	5.8	6.5	7.0	7.2

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Cloud cover (%)	62	62	62	62	62	59
Clear days (≤ 30% cloud)	5	5	6	6	5	6
Partly cloudy days (30–70%)	11	10	11	9	12	12
Cloudy days (≥ 70%)	14	13	15	15	14	12
Relative humidity (%)	83	82	80	78	78	76
Wind speed (mph)	7.9	7.9	8.1	7.7	6.4	5.7

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Cloud cover (%)	55	54	54	54	59	63
Clear days (≤ 30% cloud)	7	8	9	10	7	5
Partly cloudy days (30–70%)	13	12	10	10	11	11
Cloudy days (≥ 70%)	11	11	11	12	12	15
Relative humidity (%)	72	73	75	77	79	83
Wind speed (mph)	5.2	5.1	5.8	6.5	7.0	7.2

Methodology & sources

Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Dover (NOAA GHCN station USC00072730), about 19 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 →