What is the hottest month at Gateway Arch?

July, with an average high of 89°F and an average low of 69°F at Cahokia (NOAA 1991–2020 normals). The station averages 40 days a year at or above 90°F.

How cold does Gateway Arch get in winter?

January is the coldest month, averaging a low of 22°F and a high of 41°F at Cahokia. About 97 nights a year drop to freezing or below.

Does it snow at Gateway Arch?

Yes. Cahokia averages 13.8 inches of snow a year, mostly in January, February, March and December. Higher ground in the park gets more.

When is the rainy season at Gateway Arch?

July is the wettest month on average (5.0 inches of precipitation at Cahokia); the station's annual total is 42.8 inches.

How many hours of daylight does Gateway Arch get?

About 14h 51m on June 15 and 9h 29m on December 15 (sunrise 5:36 AM, sunset 8:27 PM in June; 7:11 AM to 4:40 PM in December, America/Chicago time).

What is the best month to visit Gateway Arch for weather?

By NOAA's normals, average highs sit between 55°F and 85°F in March, April, May, June, September, October and November. Of those, March, April, May, June, September, October and November are also well below the park's peak crowds. Weather in the park varies with elevation; this is the Cahokia station.

Weather by month

Gateway Arch weather, month by month

Last verified October 6, 2026NOAA 1991–2020 normalsAmerica/Chicago time

Average highs, lows, rain, snow and daylight for every month. Measured at the Cahokia (400 ft, 4 mi from Gateway Arch Visitor Center).

looking up at the curve of the Gateway Arch against the sky — Photo: NPS Photo/Sue Ford

Jul high: 89°F; hottest month
Jan low: 22°F; coldest month
Rain + snowmelt: 42.8in / yr; wettest: Jul
Snowfall: 13.8in / yr; Dec–Mar
Days ≥ 90°F: 40/ yr
Nights ≤ 32°F: 97/ yr

Cahokia

Month by month

Normals are 30-year averages (1991–2020). Crowds = each month’s share of the park’s busiest month, from NPS visitor counts. Sunrise and sunset are for the 15th of each month in 2027.

Average high and low, every monthbars run from the low to the high · tan strip = precipitation

Month	High	Low	Rain	Snow	Wet days	Sunrise	Sunset	Daylight	Crowds
Jan	41°	22°	2.7″	4.9″	9	7:17 AM	5:03 PM	9h 46m	11
Feb	46°	26°	2.3″	3.7″	8	6:52 AM	5:38 PM	10h 46m	13
Mar	56°	35°	3.5″	1.2″	10	7:12 AM	7:07 PM	11h 55m	35
Apr	68°	45°	4.6″	0.3″	12	6:25 AM	7:37 PM	13h 12m	32
May	76°	56°	4.8″	—	12	5:49 AM	8:05 PM	14h 16m	36
Jun	85°	65°	4.3″	—	10	5:36 AM	8:27 PM	14h 51m	49
Jul	89°	69°	5.0″	—	8	5:48 AM	8:25 PM	14h 37m	100
Aug	87°	67°	3.1″	—	8	6:15 AM	7:56 PM	13h 41m	46
Sep	80°	59°	3.4″	—	7	6:42 AM	7:10 PM	12h 28m	29
Oct	70°	46°	3.0″	—	8	7:10 AM	6:23 PM	11h 14m	26
Nov	56°	35°	3.3″	0.8″	8	6:43 AM	4:48 PM	10h 05m	22
Dec	45°	27°	2.8″	2.9″	10	7:11 AM	4:40 PM	9h 29m	20

Sweet spot: March, April, May, June, September, October and November combine average highs between 55°F and 85°F with crowds under 60% of the peak month. Check what is open in those months — quiet can also mean closed roads.

How to read this

These are NOAA’s official 1991–2020 climate normals for one weather station, not a model of the whole park. The station is the one with complete temperature and precipitation normals nearest to a visitor center. Highs and lows are daily averages for the month; “wet days” are days with at least 0.01 inch of precipitation. Mountain parks can be 10–20 °F cooler at their high points than at the station, and the NPS weather page for Gateway Arch is the place for current conditions and seasonal closures.

Sunrise and sunset are computed with the NOAA solar equations for the park’s coordinates and shown in America/Chicago time for the 15th of each month of 2027; they are accurate to about a minute.

Sources · 3

1.U.S. Climate Normals 1991–2020 — monthly normals station inventory · National Centers for Environmental Information (NOAA)
2.Gateway Arch National Park — Weather (nps.gov) · National Park Service
3.Gateway Arch National Park — Visitor Use Statistics · National Park Service (IRMA)

FAQ

Gateway Arch weather questions

What is the hottest month at Gateway Arch?: July, with an average high of 89°F and an average low of 69°F at Cahokia (NOAA 1991–2020 normals). The station averages 40 days a year at or above 90°F.
How cold does Gateway Arch get in winter?: January is the coldest month, averaging a low of 22°F and a high of 41°F at Cahokia. About 97 nights a year drop to freezing or below.
Does it snow at Gateway Arch?: Yes. Cahokia averages 13.8 inches of snow a year, mostly in January, February, March and December. Higher ground in the park gets more.
When is the rainy season at Gateway Arch?: July is the wettest month on average (5.0 inches of precipitation at Cahokia); the station's annual total is 42.8 inches.
How many hours of daylight does Gateway Arch get?: About 14h 51m on June 15 and 9h 29m on December 15 (sunrise 5:36 AM, sunset 8:27 PM in June; 7:11 AM to 4:40 PM in December, America/Chicago time).
What is the best month to visit Gateway Arch for weather?: By NOAA's normals, average highs sit between 55°F and 85°F in March, April, May, June, September, October and November. Of those, March, April, May, June, September, October and November are also well below the park's peak crowds. Weather in the park varies with elevation; this is the Cahokia station.

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