tick and flea in rainy season, what works for Kitty

Kitty is 6 years old, mixed breed, and he goes out to the park by our building every morning. In rainy season the ticks come out a lot, and last year I found 3 on him in one week. Very gross. Now I put the spot-on medicine on the 1st of every month, even when it is raining, and I set an alarm on my phone so I don't forget. The vet said the spray is not good enough alone, and the collar only helps a bit. I also wash his bed every Sunday with hot water and I vacuum the sofa more often. Ticks hide in the carpet. Kitty hates the bath but he survives it.