The site Wunderground.com has sections dedicated to the weather of diverse parts of the United States and the World. There you can find one page about the San Luis's weather.

In the left side of the screen you can get to the following stats: pressure, humidity, visibility, temperature, etc. On the right side you will see the forecast for the next days.

URL of the San Luis, Missouri, wather: http://www.wunderground.com/US/MO/Saint_Louis.html