Morning commuters sat in traffic jams Wednesday as the first storm of the season dropped more than an inch of rain in parts of the Santa Clarita Valley and turned the Newhall pass into a nightmare.

Two separate big-rig crashes stalled traffic through the morning, but weather forecasters said better driving conditions were ahead, with clear skies and higher temperatures starting today and continuing through the weekend.

A crash of a tractor carrying two trailers Wednesday morning on Interstate 5 just south of the Newhall area forced closure of all lanes for half an hour and slowed traffic for hours afterward, a California Highway Patrol report said.

Just after 5 a.m., a three-axle tractor truck with two trailers traveling in the rain on southbound I-5 near Gavin Canyon made an abrupt turning movement, causing its trailers to collide into each other and into its tractor, the report said.

The truck, which did not hit any other vehicles, blocked all four lanes and the freeway’s left shoulder, the report said.

The vehicle could not be moved because of a broken driveshaft and two broken wheels, but officers were able to clear a narrow path on the right shoulder for vehicles to pass through, one by one, at about 5:35 a.m., according to the report.

All other southbound traffic was diverted off the freeway at Calgrove Boulevard and onto The Old Road. All southbound lanes were re-opened at about 7:10 a.m., the report said.

A couple of hours a later, a second crash involving an oil spill blocked traffic on the northbound 405 freeway in Mission Hills and affected those commuting into the Santa Clarita Valley, officials said.

At about 10:20 a.m., officers closed nearly all lanes of the 405 except for the carpool lane just south of Rinaldi Street after a big rig jacknifed and spilled about 40 gallons of diesel fuel that covered the first, second and third lanes, CHP officer Rob Lund said.

The lanes were re-opened at about 12:07 p.m., he added.

CHP and other officials said they also received numerous calls about minor accidents throughout the day.

“Drivers just don’t slow down,” Lund said.

Sheriff’s deputies advised drivers to take extra precautions when traveling in rainy conditions.

“When it’s the first rain of the season, it generally washes away oil and slick grease that is on the asphalt and streets,” said Los Angeles County sheriff’s Lt. Robert Lewis. “If people don’t drive slower than they usually drive ... we have accidents that occur.”

Skies are due to clear today and weak Santa Ana winds will roll in on Friday, said National Weather Service meteorologist Dave Gomberg.

Weather experts canceled flash flood watches for burn areas affected by the Station Fire Wednesday at 2 a.m., while they canceled high-wind advisories for the Santa Clarita Valley at noon, Gomberg said.

Firefighters did not respond to any mudslides Tuesday night or Wednesday in the Santa Clarita Valley, Los Angeles County fire officials said.

“Everything’s just kind of quieting down for the tail end of the storms,” Gomberg said Wednesday afternoon.

Rainfall amounts varied around the valley, with 1.9 inches of rain falling in Newhall by noon Wednesday and half an inch falling in Saugus by 5 p.m., weather officials said.

Mountain areas saw about 3 inches of rain by noon, Gomberg said.

Temperatures will reach the mid- to high-80s Thursday, which should last through Saturday before temperatures drop again, Gomberg said.

Weak northeast Santa Ana winds traveling about 10 mph to 20 mph are also expected Friday, which should help keep temperatures warm, he added.

“When (wind) goes (in) more of a north or northeast direction,” he said, “that tends to warm it up and dry things out.”