The thunderstorms that rolled across the Valley on Sunday afternoon and evening produced vivid lightning flashes across the sky that were accompanied by booming thunder and some pea-sized hail.

“It was probably a more prolific lightning show than maybe we were anticipating,” National Weather Service meteorologist Brian Ochs said Monday morning.

The storms had been forecast because of the unstable air masses colliding over California — colder air at higher elevations hitting the warmer air that created relatively balmy temperatures on Saturday — Ochs said.

February is a little early for such storms to hit the Valley, which usually sees them later in March and April, he said.

Sunday’s downpours in Fresno totaled 0.6 of an inch, raising the area’s rainfall since Oct. 1 to 9.83 inches. That more than 4 inches above the average rainfall by this time of year of 5.71 inches, and only about an inch less than the total average seasonal rainfall of 10.99 inches, Ochs said.

The storms also brought more snow to the Sierra, with a foot to 18 inches falling at the 6,000-foot level and higher, he said.

Soaked ground and colder weather produced the inevitable fog Monday morning, and Ochs said the forecast calls for foggy nights and mornings this week and the possibility of frost in outlying areas as overnight temperatures dip near freezing.

Temperatures will start to warm up again later in the week and could be back in the mid to upper 60s by Thursday and Friday, but more wet weather could be on the way by Saturday night into Sunday morning, Ochs said.