After heat wave ends, rain could roll into SLO County

From heat to fog to even possible rain showers, the weather across San Luis Obispo County for the next few days will feature distinct variety.

John Lindsey, who has forecast local weather for more than two decades, said that today will be the second half of a two-day hot spell. Temperatures in Paso Robles should reach 104 degrees — equal to Tuesday’s mark — while San Luis Obispo will be near 90.

The heat will give way to foggy morning skies and cooler temperatures on Thursday. On that day and Friday, highs in the North County will fall back into the upper 90s, and San Luis Obispo will be near 82 degrees, said Lindsey, a community relations specialist for PG&E.

Then a low-pressure system will develop over the county Saturday, and it could “pull subtropical moisture from the desert Southwest,” Lindsey said. “If this condition develops, scattered rain showers and possible thunderstorms could develop over the weekend.”

The resulting cloud cover would cool things down further, with North County highs falling into the 80s and San Luis Obispo dropping to the mid-70s.

Lindsey cautioned that storm systems such as the one forecast for the weekend are notoriously difficult to predict, so it is possible no rain will come at all.

That said, September showers are not unusual. Lindsey said the average rainfall for the month in San Luis Obispo is nearly a third of an inch. In 1976, a tropical cyclone veered from Mexico toward California and brought nearly 4 inches of rain to the region, he said.

Hot days are also not unusual in September. That’s because wind patterns start changing as autumn nears. Rather than strong winds blowing off the ocean, warm, dry breezes start blowing from the inland areas toward the sea.

As a result, Lindsey said September is usually warmer than August for daytime temperatures in San Luis Obispo and along the coastline.