What we NEED is colder winters.
What you need is more precipitation. Colder winters might help that happen, but they are not what you need, per se. What you need is lower global temperatures, especially in ocean waters, so that your regional climate is no longer fucked up by climate change.
I understand that the water-harvesting scenario in my previous post depends on rainfall -- of which California has seen practically none for several years in a row. But that's no reason not to start investing in the kind of infrastructure that could help alleviate these concerns over the long term.
Fixing climate change is going to take some time and effort, on several fronts simultaneously. We all have a role to play.