As in Southern California, San Francisco has also been struggling with a giant mass of high pressure that is deflecting storms away from California -- a pattern that has remained consistent throughout December.
"How long this will continue, I don't think anyone knows," Null said.
The situation is even more grim in Southern California.
On average, downtown Los Angeles gets more than an inch of rain in November and more than 2 in December. But this year, only one-hundredths of an inch of rain fell in November, and the same amount fell in December. In fact, there has been no substantial rainfall in downtown Los Angeles since February.
Since Oct. 1, downtown L.A. has seen only a measly 0.12 inches of rain.
It's part of a larger weather trend for Southern California: Over the last seven years, maximum temperatures during the fall have gotten hotter and there has been less rain.
This October and November were the hottest in 122 years of record keeping for the region.
For downtown Los Angeles, this is shaping up to be the driest March-through-December period on record, with a paltry 0.69 inches beating out the 1.24 inches that fell during the same 10-month period in 1962.
"We'd have to have a dramatic turnaround to have a wet winter," said climatologist Bill Patzert of NASA's Jet Propulsion Laboratory in La Canada Flintridge.
"It's certainly not an auspicious start," said UCLA climate scientist Daniel Swain.