Gateway Arch Weather: Forecasts, Climate, and Current Conditions

By David Sanchez · Data: National Park Service · ← Complete guide Gateway Arch

Gateway Arch stands along the Mississippi River in St. Louis, Missouri, right in the heart of the North American continent. That location gives it a humid continental climate: hot, muggy summers, cold winters with possible snow, stormy springs, and often bright autumns. The four seasons are sharply defined, with little in the way of a gentle transition.

Gateway Arch Climate Month by Month

The table below shows average daily temperatures (including nighttime) and normal sunshine levels in St. Louis, based on NOAA records:

These averages include nighttime temperatures. Mid-afternoon temperatures run considerably higher in summer and lower in winter. November is the grayest month (46% sunshine), while July peaks at 68%. Even in January, St. Louis sees sunshine about one day out of two.

Season-by-Season Climate

Winter (December to February)

Temperatures hover around 34°F in December and February, then drop below freezing in January (average: 29°F). Snow falls several times during the season, though it doesn't always stick around. Wind can make it feel much colder than the thermometer suggests, especially on the open plaza facing the Mississippi River.

The park stays open year-round (except Thanksgiving, Christmas, and New Year's Day), with shorter hours outside summer. Crowds are light. The Arch against a snowy backdrop is quite striking, and you'll have the grounds largely to yourself.

Spring (March to May)

The warm-up comes quickly, from 45°F in March to 66°F in May. Spring is also the season for severe thunderstorms across the Midwest. Convective storms can flare up within hours, sometimes bringing hail or strong winds. Missouri sits on the edge of Tornado Alley, so tornado warnings in the region aren't unusual from April through June.

In April and May, temperatures are ideal for the plaza and the museum, while visitation remains moderate before the start of the peak season.

Summer (June to August)

This is peak season. The park extends its hours until 8 p.m. on Fridays and Saturdays from late May through Labor Day. Average temperatures reach 75 to 80°F, but humidity (warm air moving up from the Gulf of Mexico) makes it feel 9 to 18 degrees hotter than the thermometer indicates. An outing on the plaza in mid-afternoon can quickly become strenuous.

Sunshine peaks in July (68%), making for great photos of the Arch beneath a blue sky. Late-afternoon thunderstorms are part of the summer pattern, though.

Fall (September to November)

In our view, fall is the most pleasant time of year: 70°F in September, 58°F in October, plenty of sunshine (60 to 63%), and fewer visitors after Labor Day. November turns gray and cold, but September and October offer ideal conditions for strolling across the plaza and taking in the view from the top.

Is Gateway Arch Cold or Hot? Benchmarks and Extremes

St. Louis is a city of sharp temperature swings. Local records climb above 104°F and can approach -4°F when wind chill is factored in. The Arch itself, rising 630 feet, is especially exposed to the wind. At the top, it can feel several degrees colder than it does on the plaza, no matter the season. Keep that in mind before heading up in a T-shirt in November.

What to Wear by Season

Winter: a warm coat (down or heavy wool), hat, gloves, and waterproof shoes. If you're going to the top, add an extra layer. The wind at 630 feet doesn't let up.

Spring: several light layers and a lightweight rain jacket in your bag. Keep an eye on weather alerts. A clear morning can turn stormy by early afternoon.

Summer: lightweight, breathable clothing, a wide-brimmed hat, SPF 50+ sunscreen, sunglasses, and a bottle of water. The concrete and granite plaza reflects and amplifies the heat. Drink water regularly. Avoid direct sun from noon to 4 p.m. if you're traveling with young children.

Fall: versatile clothing and a windbreaker for cool October and November mornings. Keep it simple and practical.

Alerts and Conditions to Watch

Thunderstorms and tornado risks (April to September). Convective storms develop quickly in the region. Check National Weather Service alerts before heading out, and if a tornado warning is issued, go inside the Visitor Center or museum immediately, below ground level.

Mississippi River flooding. The park borders the river. Flooding can temporarily close the plaza and green spaces, especially in spring after heavy rain or snowmelt upstream. Check conditions on the NPS website before you go.

Extreme heat (June to August). A heat index of 100 to 104°F is possible on the most humid days. Sensitive groups, including young children and older adults, should avoid the plaza in mid-afternoon and visit the air-conditioned museum instead.

Frequently Asked Questions