Fortunately for this particular case, Berkeley winter temperature hasn't seen a record low below 25 degrees F in the last 30 years. Or more, Wikipedia doesn't go back further than that.
That's actually correct, though you can also tune them for harsher local weather. I actually visited a heat-pump factory in Guangdong back in March. They make heat-pumps for residential projects in both freezing cold Harbin (Northern China) and hot as hell Guangdong (Southern China). Those are different SKUs that get tuned based on expected regional needs. The temp-vs-efficiency curves get all wacky but it still works. They also had a new product that combines two heat pumps: one for summer, one for winter.