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Zion, Illinois climate

Dfb Warm-summer humid continental

Zion has a strongly seasonal cool-temperate climate (Warm-summer humid continental, Köppen Dfb). The hottest month is July with an average daily high near 81°F, while the coldest is January averaging around 16°F at night. Around 35 inches of precipitation falls each year, peaking in June (4.5 inches) and easing off in January (1.4 inches).

☀️ Summers

Warm

Highs near 81°F in July.

About 8 days a year above 90 °F

❄️ Winters

Very cold

Lows near 16°F in January.

About 128 freezing nights a year

🌧️ Rain

Moderate rainfall

About 35 in of rain a year.

Wettest in June

⛅ Sky & trend

Often cloudy

Cloudy skies much of the year.

−0.5 °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

Zion climate normals (1991–2020)

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°F)	31	34	44	56	67	77	81	80	73	61	48	36
Avg temp (°F)	23	26	36	46	56	66	72	71	63	52	40	29
Avg low (°F)	16	18	27	36	46	56	62	61	54	43	31	22
Precipitation (in)	1.4	1.5	2.2	3.8	3.9	4.5	3.5	3.6	3.6	3.3	2.3	1.9

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Avg high (°F)	31	34	44	56	67	77
Avg temp (°F)	23	26	36	46	56	66
Avg low (°F)	16	18	27	36	46	56
Precipitation (in)	1.4	1.5	2.2	3.8	3.9	4.5

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°F)	81	80	73	61	48	36
Avg temp (°F)	72	71	63	52	40	29
Avg low (°F)	62	61	54	43	31	22
Precipitation (in)	3.5	3.6	3.6	3.3	2.3	1.9

How often — frequency of weather events

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Days with measurable rain (days)	8	8	10	12	13	11	10	12	12	12	10	9
Days with high ≥ 90°F (days)	—	—	—	—	0.2	2	4	2	0.6	—	—	—
Days with low ≤ 32°F (days)	27	25	21	9	1	0.1	0.2	0.1	0.1	4	16	26

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Days with measurable rain (days)	8	8	10	12	13	11
Days with high ≥ 90°F (days)	—	—	—	—	0.2	2
Days with low ≤ 32°F (days)	27	25	21	9	1	0.1

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Days with measurable rain (days)	10	12	12	12	10	9
Days with high ≥ 90°F (days)	4	2	0.6	—	—	—
Days with low ≤ 32°F (days)	0.2	0.1	0.1	4	16	26

Sky & atmosphere

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Cloud cover (%)	76	73	76	80	79	76	68	64	59	65	70	75
Clear days (≤ 30% cloud)	1	2	0.9	1	2	2	3	4	7	6	3	2
Partly cloudy days (30–70%)	9	9	10	7	7	8	11	12	10	9	9	8
Cloudy days (≥ 70%)	21	17	20	22	22	20	17	15	13	16	17	20
Relative humidity (%)	89	85	80	77	77	77	75	74	74	76	81	88
Wind speed (mph)	9.6	9.5	9.0	8.9	7.6	6.2	5.8	5.5	6.5	7.8	8.5	8.7

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Cloud cover (%)	76	73	76	80	79	76
Clear days (≤ 30% cloud)	1	2	0.9	1	2	2
Partly cloudy days (30–70%)	9	9	10	7	7	8
Cloudy days (≥ 70%)	21	17	20	22	22	20
Relative humidity (%)	89	85	80	77	77	77
Wind speed (mph)	9.6	9.5	9.0	8.9	7.6	6.2

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Cloud cover (%)	68	64	59	65	70	75
Clear days (≤ 30% cloud)	3	4	7	6	3	2
Partly cloudy days (30–70%)	11	12	10	9	9	8
Cloudy days (≥ 70%)	17	15	13	16	17	20
Relative humidity (%)	75	74	74	76	81	88
Wind speed (mph)	5.8	5.5	6.5	7.8	8.5	8.7

Methodology & sources

Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Chicago Waukegan Rgnl AP (NOAA GHCN station USW00014880), about 3 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 →