Hey Lindsey,
I’m going to answer this here, too. Just because.
The weather in the local mountains is unpredictable, especially this time of year. But don’t think that snow = “no go.” It just requires extra care and flexibility.
That rain we had last Wednesday? It generated snow in the mountains. SoCal Hiker Martha tried to hike up Cucamonga Peak on Friday and didn’t make the summit because of the snow. But she had a wonderful hike and saw some awesome scenery. If that’s good enough, go for it!
The caveat is that traveling in snow makes navigation tricky. You really need to have a map and compass and the know-how to use them.
As for Mt. Wilson, if you check our Mt. Wilson page there’s a link to the observatory webcam — that’ll give you a great idea of conditions at the top. It’s below 6,000 feet, so while it can (and does occasionally) get snow, it’s less likely. So that is generally a pretty safe bet.
Baldy is much higher, but if you check with the ski lift, they can probably tell you what the conditions are like.