I'm not going to give medical advice, but here's what I do when weather is predicted.
I check the morning weather forecast. If the boat has a marine radio, listen to the local weather for our area.
What works great for me is to use the "My Radar" app on my smart phone. The only thing this app does, and does well, is to give you near real time (within 10 or 15 minutes) weather radar. Tracking the weather thatt will affect you is more useful than a general forecast, which tells you what is probable, vs what is happening now. Try it and see what I mean.
http://myradar.com
This one is on Apple as well as Android, and it's free version works quite well.
With it you can track a storm cell and see if it's headed your way or not.
If weather is predicted, I'll check it ever 30 minutes or so, this way I'm not caught off guard.
Often storms may track away from you, or if they are headed for you, you can head for a safe place. If needed use anyone's dock.
Yes, it's a tough call to rent or not, but you may have a full early day of boating if the storms don't hit until 3pm or later, if at all.
Be safe, have fun!