We can definitely drop down to 30 degrees in winter, at night -- it is not uncommon at all. If not 30 degrees, then 40 degrees at night. A low daytime temperature might be 50 degrees, but more than likely 60-something or low 70s.
The El Nino rain (which was what Texas recently got slammed with) is looking more and more likely -- sometimes El Nino patterns will form and then dissipate, producing nothing very significant. However, this time it looks like El Nino is forming and is going to stick. It doesn't look like it is going to dissipate before winter. If it comes to fruition and produces the strong weather systems that are predicted, there will likely be a LOT of heavy, constant rain. We're not talking just light sprinkles, or showers that last 30 minutes and then go on their merry way. A strong El Nino will pack quite a punch, and since SoCal is not really prepared for such heavy rain on a constant basis, it will also cause lots of mayhem before it brings drought relief.
But... there is still time for El Nino to weaken a bit, or fizzle out completely. It doesn't look like that will happen, but we'll see!