SAN FRANCISCO—Northern California endured its fourth round of blackouts in two months amid high winds, a new norm as the state’s utilities try to prevent deadly wildfires.

But the newest outages to 48,000 customers by PG&E Corp. ended up being far smaller than the 300,000 that the utility had put on notice of shutoffs on Tuesday. PG&E halved that number Tuesday night, and removed another 83,000 on Wednesday after reports of some precipitation and high humidity that moved in with a mostly dry-weather system that officials...