Water/rain in steering column

I recently bought a 1993 Aerostar. When I go to drive it after it rains as soon as I turn the steering wheel a good deal of water comes from the bottom of steering column right into my lap! Can any one tell me why this happens and what I can do to fix it? I would appreciate any help.Thank you.

Check the rubber boot at the firewall.

I’ll do that. Thank you.