Out of curiosity, I just checked the DL app. A number of outdoor attractions are closed, mostly at DCA.
DL: Alice, Teacups, Canal Boats
DCA: Zephyr, Incredicoaster, Jellyfish, Luigi's, RSR
Oddly, the Ferris wheel just says, "Standby line not currently offered," which sounds like "closed" to me.
On the other hand, GRR only has a 5-minute wait, so if you're already wet from the rain, go for it!
The radar shows heavy rain heading toward Anaheim and sticking around until 1:00 or 2:00 a.m., so I wouldn't lay a bet on any of the above rides reopening tonight.