Gateway Arch National Park weather in May

May in Gateway Arch National Park: warm, rainy — a great time to visit.

Updated September 2026 · climate normals from ERA5 reanalysis

Gateway Arch National Park🇺🇸 United States · Great Lakes & Midwest · National park79
  1. 65Jan
  2. 73Feb
  3. 77Mar
  4. 87Apr
  5. 79May
  6. 66Jun
  7. 57Jul
  8. 66Aug
  9. 81Sep
  10. 87Oct
  11. 78Nov
  12. 71Dec

#4 of 12 months in Gateway Arch National Park · #766 of 1413 destinations to visit in May · comfort 79/100 (tier B)

Days
26°C
Nights
13°C
Wet days
11
Sun
10 h
Humidity
70%
Daylight
14 h
Gateway Arch National Park, United States
Photo: James L · Pexels

Traveller notes on Gateway Arch National Park in May

Notes from nearby St. Louis (1 km away)

Gateway Arch National Park doesn't have its own notes for May yet — these are about St. Louis, close enough to share the season.

Ask the Saint Louis forum for the best time of year and the answer keeps coming back the same: May, then later September into early October, from both a weather and an outdoor-events point of view. The reasoning is what follows it - June through early September is described as quite hot and humid, not New Orleans hot but close, and worth avoiding where you have the choice. May gets the festival calendar without the swelter. The trade-off is water: it is one of the wettest months on the calendar here, though it arrives in bursts rather than all-day grey. The record: 25.6C days, 13.2C nights, 9.8 precipitation days carrying 139.1mm between them, humidity near 70 percent, 10 hours of sun and AQI 53.
GatewayMayShowers · May · 1 month ago · about St. Louis · Read more on Tripadvisor ↗

Other months in Gateway Arch National Park

Gateway Arch-forum reviews on a January visit describe wind off the Mississippi as genuinely intense, posters naming this a real reason to pack accordingly regardless of the daytime temperature. Regulars call tram lines genuinely nonexistent this time of year, several posters naming no waiting for either the tram or the movie theater as a real advantage of visiting in January. Posters call the weather genuinely milder than expected, several regulars naming prolonged extreme cold as rare despite the calendar. Regulars call one January tram ride memorable, a reviewer recalling snow starting to fall while riding up to the top. Posters recommend a January trip for anyone wanting the arch without crowds, several regulars naming this roughly eleven percent of peak visitation as the real draw for a quiet visit. The record: 5C days, -4.5C nights, 64.5mm across over 5 days and 69 percent humidity.
GatewayArchJanuaryRegular · January · 1 month ago · Read more on Tripadvisor ↗
Gateway Arch-forum threads on a September visit call this genuinely one of the cheaper windows, posters describing flight and accommodation rates as typically their lowest once school is back in session and Labor Day has passed. Regulars call tram tickets worth booking ahead regardless of the calmer September crowds, the arch remaining the most-visited site in St. Louis and capable of selling out even outside peak summer. Posters recommend the first tram of the day for the smallest crowd, security described as taking five to ten minutes even during busier stretches. Regulars call the ride itself brief, roughly four minutes up, seven to nine at the top and three back down, each car holding five people. Posters recommend watching the visitor center's film before heading up, several regulars calling it a worthwhile primer on the arch's history. The record: 28.9C days feeling like 30C, 14.8C nights, an extraordinarily high 88.6mm across nearly 5 days and 60 percent humidity.
GatewayArchSeptemberRegular · September · 1 month ago · Read more on Tripadvisor ↗
Gateway Arch-forum threads on a summer visit describe the heat as a real factor, one visitor reporting a genuinely unbearable walk down from the arch at a hundred and two degrees Fahrenheit. Regulars call the tram worth planning around time of day, the enclosed pod cars capable of feeling genuinely stuffy and short on air once temperatures climb later. Posters recommend early morning as the clear best window, both the outdoor walk and the tram considerably more comfortable before the day's heat builds. Regulars call the museum and grounds still worth a full visit regardless of the tram ride, indoor space offering real relief from the August heat outside. Posters recommend checking tram wait times directly, popular slots capable of building a real line even on a hot day. Regulars call real water and sun protection standing advice for the outdoor portions of any summer visit. The record: 30.9C days feeling like 34C, 18.8C nights, 114.7mm across 8 days and 71 percent humidity.
GatewayArchAugustRegular · August · 1 month ago · Read more on Tripadvisor ↗
Gateway Arch-forum reviews on a February visit describe conditions as genuinely cold, one visitor recalling temperatures near the low twenties Fahrenheit at the grounds. Posters recommend checking for a clear or mostly clear day, the tram ride up and the views both considerably more rewarding under blue sky than a flat gray afternoon. Regulars describe the visitor experience as largely indoor and weather-independent once inside, the museum and tram both sheltered regardless of what's happening outside. Posters call a light system entirely possible this time of year, one reviewer describing the tram ride during a snow shower as genuinely memorable rather than a disappointment. Regulars recommend real winter layers for the walk to the arch, wind off the river a real factor in how the cold feels. Posters call February a quiet, uncrowded month for a visit. The record: 9.1C days feeling like 6C, -2.9C nights, a notably high 6.5cm of fresh accumulation and 66 percent humidity.
GatewayArchFebruaryRegular · February · 1 month ago · Read more on Tripadvisor ↗

Add your own note from Gateway Arch National Park's card on the map.

Gateway Arch National Park climate normals — May

Daytime high26°C / 78°F🌤 warm
Nighttime low13°C / 56°F
Feels like (high)26°C / 79°F
Rainfall143 mm / 5.6 in🌧 rainy
Rainy days11 days
Humidity70%💧 humid
Dew point13°C / 55°F
Sunshine10 h/day
Daylight14.3 h
Wind17 km/h / 10 mph
Air quality (US AQI)53🙂 moderate

Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.

Crowds in Gateway Arch National Park in May

How busy the place itself is — school and mass holidays, the months an editor tagged, and how sought-after the weather makes them. Never part of the comfort score.

Shoulder seasonan ordinary month(estimated)

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Peak crowdsBusyShoulder seasonQuiet

Best months for Gateway Arch National Park's weather

Ranked by this destination's own climate comfort score across the year — a different thing from how busy it gets (see Crowds above).

Fair weatherGateway Arch National Park's best weather comes in April, September and October — separate windows, not one continuous season.

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Best weatherFair weatherToughest weather

What's on in Gateway Arch National Park in May

Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.

  • Opening

    Riverboat cruise season

    1 Mar – 30 NovSummer season opens

    The paddlewheelers run off the levee from March to November, with the lock-and-dam trips added in October. Outside those months the riverfront is just a windy set of steps. Source ↗

  • Hazard

    Mississippi spring flood

    15 Mar – 30 Jun · usuallyFlood seasonClosures

    Snowmelt and spring rain from half a continent arrive here, and the cobblestone levee below the Arch goes under most years — sometimes the riverfront path with it. The Arch itself never closes for it; the boats do. Source ↗

What's on around the world in May →

Nearby, and something's on

Within 300 km of Gateway Arch National Park — a day trip or a short hop — with something on this month. Never part of the comfort score.

Where is Gateway Arch National Park?

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Gateway Arch National Park in May — FAQ

Is May a good time to visit Gateway Arch National Park?
May in Gateway Arch National Park: warm, rainy — a great time to visit. It ranks #4 of 12 months for Gateway Arch National Park on SeasonMap's comfort score (79/100).
What is the weather like in Gateway Arch National Park in May?
In May, Gateway Arch National Park averages a daily high of 25.7°C and a low of 13.2°C, with about 142.5 mm of rain over roughly 10.5 rainy days.
What is the air quality in Gateway Arch National Park in May?
Gateway Arch National Park has a mean US Air Quality Index of about 53 in May.

Within 300 km: St. Louis' Botanical Garden spring bloom around 1 Apr – 5 May.