I seem to remember it being the last week of '89. It was 17'F Saturday morning when it hit. Friday's high the day before was 38'F. Not good for the Central Valley.
Waterlines broke, big-block boat motors cracked, pool heaters split, pool pumps had their lids 'lifted' an inch above where they'd been screwed down. Every pool that hadn't run a pump overnight had two inches of ice, the pump frozen, and other problems that could only be detected later (when you could thaw things out and get things primed again).
This was considered an 80 (eighty) year event. Here's what you do if it gets anywhere near the low twenties: run your pool or spa pump from 9pm to 9am. The electricity won't cost anywhere near replacement costs.
If you have solar on a pool, drain it. Most have a valve that closes during operation (to keep the water in) and will open to drain (allow air into the system) when the solar is off. If in doubt, drill a hole in both lines headed to the roof and plug/plumb them later. Some thoughtful installers put drain valves in, if so, open them first.
Wrap hose bibs and exposed waterlines outside with split-foam pipe insulation(at Home Depot or Lowes- 1/2" or 3/4") and finish with black tape (also available there).[Cutting the foam with a razor knife is an art, don't fret- just imagine you're building a picture frame when you get to any 90's] *Some homes were built with a waterline entering near the garage and going over it through to the water heater, etc. Insulate this line too, if this is your case (not too common but some folks came home to a flooded house when this pipe froze).
For folks in the foothills who happen to have leaks (like Sierra Wasp) it's still a good thing [and I commend him for his sacrifice]. Our lakes need the water. Our fish need the water. And, you'll be doing the 'green' thing. Matter of fact, I'll be entering the next bass tournement running a sailboat. How green is that?
You and I are both up way too late contemplating this speculative subject. Your sense of history on this is very good and better than mine, by far!!!
Aha! Thanks, budwiesest!!!