If you planning to travel to Old Post Office, St Louis, Missouri, here is your 6-day travel weather forecast to make sure you have all the essentials needed during your stay. Start your day when the sunrises at 10:40 AM. The temperature feels like 80.85 with a humidity level of 57 so dress accordingly. Cloud coverage is 4 percent with visibility at 14.7 percent. Today’s UV index is 3, don’t forget the sunscreen if you need it! Today’s winds are traveling south-southeast at a speed of 10 MPH. At the end of the day don’t miss the sunset at 1:28 AM.