Jefferson National Expansion Memorial National Memorial

The Old Courthouse is open daily from 8:00 a.m. to 4:30 p.m., except Thanksgiving, Christmas and New Year's Day. Admission is free.
Winter Hours
For most of the year, the Gateway Arch and Museum of Westward Expansion are open daily from 9:00 a.m. to 6:00 p.m.  
Summer Hours
The remainder of the year from Memorial Day through Labor Day, the Arch and Museum are open from 8:00 a.m. to 10:00 p.m.

Climate
Summers are often hot and humid, with average temperatures in the high 80 or 90 degrees Fahrenheit; autumn and spring are mild and pleasant; winters are rarely harsh, with average temperatures about 30 degrees Fahrenheit.