Parts of the San Francisquito Creek are threatening to overflow its banks. The creek runs through East Palo Alto, Menlo Park and Palo Alto.
Local fire agencies have been calling residents and businesses near the creek warning them of potential flooding in the area.
At least several hundred people from a part of East Palo Alto near University Avenue and along East Bayshore Boulevard have left their homes. Police officers are also driving along neighboring streets and broadcasting the warning to residents.
A fire spokesperson says the creek is already at least four feet above flood stage. The creek is likely to overtop its banks near the Chaucer Creek Bridge.
Free sandbags are available at the Palo Alto Airport Terminal, and also at Mitchell Park near The Little League field.
In the North Bay, heavy rain contributed to a watery mess along Highway 121 at the transition to Highway 12 in Sonoma County. Major flooding kept the intersection closed for the better part of several hours this afternoon.
All of the water came from nearby Sonoma Creek, which overflowed its banks.
The floodwaters rapidly moved down Highway 12, inundating the vineyards and farmland in its path.
In Cotati, emergency repairs had to be made to a stretch of Stony Point Road after rushing runoff from heavy rains earlier in the day overwhelmed a drainage culvert, causing a sinkhole.
The runoff was also posing problems for places like Petaluma, where the river there crept right up to the downtown area on C Street. Some businesses had their sandbags set in case the river crept higher.
Sand bags were on standby at apartments right next to the creek at F Street. Water barely squeezed under the roadway there, but it flowed over earlier in the day.
In Penngrove, the Lichau Creek jumped its banks and soaked the community park.
In El Sobrante, the surge of rain proved too much for a creek to handle. The creek backed up and flooded as many as four homes on Appian Way Sunday afternoon. One resident says the water actually started flowing into his house.
In San Francisco, a two-mile stretch of the Great Highway was blocked off between Lincoln Way and Sloat Boulevardt. Both southbound lanes were flooded. The northbound lanes were shut down as city work crews repaired a dangling traffic light that was knocked loose in heavy winds.
The strong and steady storm pounded the seawall along coastal communities. Giant swells in Pacifica closed the local pier, while stinging rain and wind gusts up to 48 miles per hour kept most people indoors.
The weather continues to cause airport delays and flight cancellations because of low cloud ceilings and reduced visibility. There were 45 minute delays for departing flights at SFO and 20 minute delays for arriving flights.
Delays are expected to last until about 11 p.m.
Nearly 30 flights were cancelled Sunday.
No major delays or cancellations are reported at the airports in Oakland or San Jose.