Think October was a bit warm?

Cool air coming down from the Northwest will bring as much as a 20-degree drop.

The heat broke local records. But cold and rain are expected.

Cooler weather is forecast for the Los Angeles area. Finally. After a warm, dry Halloween weekend and the hottest October ever for much of Southern California, meteorologists say temperatures could drop as much as 20 degrees Monday. There’s even a 40% chance of rain Monday and Tuesday.

“It’s going to be a real shocker for Angelenos,” said Bill Patzert, a climatologist with NASA’s Jet Propulsion Laboratory in La Cañada Flintridge. “People can bring out their long-sleeved shirts — if they can find them.”

On Monday, highs in the 60s and 70s are expected in the coastal and valley areas. There’s also a chance of gusty winds, said Scott Sukup, a meteorologist with the National Weather Service.

The cool air is coming down from the Northwest, having traveled over the Gulf of Alaska.

The change in temperature and the possible rain have nothing to do with El Niño, Sukup said. Storms linked to that weather phenomenon are expected to start in January and last through March.

Unfortunately, experts say, the cooler temperatures are not going to linger.

“The low pressure is going to move east and we might get a little bit of a weak offshore flow, which will cause temperatures to rise again,” Sukup said.

So soak it up now, Angelenos.

“It’s a temporary treat for everyone,” Patzert said. “It’s a teaser.”

There is no such thing as “normal” weather for Southern California, meteorologists said, but this October was unusually warm.

According to the weather service, last month had some of the highest temperatures on record.

The average mean temperature in downtown Los Angeles was 75.6 degrees in October, breaking the record of 74.2 that had held since 1983.

At Los Angeles International Airport, the average mean temperature of 74 shattered the record of 72.5 that had held since 1958.

October also set records in Woodland Hills, Burbank, Santa Barbara and Oxnard, according to the weather service.