This time of year, Missouri tends to be very wet. Really no way to avoid it, if you want to ride. Creeks can be misleading! Or the random holes filled with water. Not sure what is worse the shock to your body of the cold weather or letting the bike swim.
If it is a quick submerge there is a chance the bike might still start. But a hot engine and cool water never mix. First, I would try to start it. If it does not start, pull the spark plug and flip the bike upside down. Kick the engine over. This helps push any water out of the top end. Flip it back over and install a sparkplug. If you do not have a spare with you, dry off the one you pulled out. Keep your fingers crossed that it starts otherwise you will be pushing the bike back. Be sure to change the air filter and oil once you get back.
What if the bike does not start and needs to be pushed back? Load up and head home. The process is similar as above. Take the spark plug out, flip upside down, and turn the engine over. Drain the oil. Change the air filter. The float bowl could also be filled with water so check that. In extreme cases, it would not hurt to go ahead and replace the exhaust packing. With fresh oil, spark plug, and air filter installed go ahead and start the bike. Oh no! It still does not start, this could mean a complete engine rebuild may be needed. Don’t fret if your mechanic skills are not up to par, take it to a local shop and let them dig into it. A good rule of thumb, always be honest about what has happened to the bike even if it is embarrassing, not just referring to the bike going swimming any instant something mechanical fails, tell the story. It helps the mechanic understand what has happened and why it happened.