What time did the Lewis and Clark expedition leave St. Louis?

In the Lewis and Clark journals it does not state specifically at what time Lewis and Clark left St. Louis. However, most of the time Lewis preferred to leave in the early morning to travel as far as possible. But it had rained during the first half of the day, so it can be supposed that Lewis and Clark left perhaps around 10:00 am rather than their usual 7:00 or 8:00 am.