I'm at the Fright Night scenario of RCT3's career mode, and the rain just ruins the mission - peeps don't want to ride on any of my rides when it rains (which is understandable in the case of open rides), and it rains almost constantly. Recalling my time played with the first game, I decided to build some covered rides, but peeps even say they won't go on those while it's raining.
Scenery roofs are also just for show - rain pours right through them and peeps won't go on rides covered by them.
In a desperate attempt, I even built some rides underground, but the peeps seem to feel the rain there, too...
Can you give me some advice about what to do?

Do you think a pool is a good idea? I love building them (I built one in every scenario this far) but in earlier levels, peeps even complained that it was too cold for a swim even when it didn't rain.

Even if no one swims, it'll still bring more people into your park, which at the very least will increase umbrella sales.

Thanks for the tips, Hesusio, they seem to work.
I've built quite some new rides and they provide a steady, even if not grandiose, profit, and I've completed the scenario on Entrepreneur level already. Now to get the excitement rating of my own coaster over 7... (It'd be easier if I could use ride events, no doubt.)

I know this is old, but I wanted to mention that the pool did bring in a lot of people and is very profitable.

Also, set your rides to wait for specific loads and eliminate the max wait time of 120 seconds, that way your rides aren't running empty, minimizing operating costs and maintenance requirements for the rides.