Issued at 755 PM PST Mon Jan 19 2026
It looks like the Northern Lights are going to be a bust tonight. The clouds are holding off, but the geomagnetic activity has plummeted from the G4 level observed this afternoon to less than G1 at the latest measurement. The issue is the orientation of the magnetic field generated by the strong coronal mass ejection. When it first hit earlier today, the incoming field was oriented south, which is opposite of the earth's magnetic field, and allows for enhanced energy transfer into our magnetosphere. Europe was getting a good display thanks to their earlier sunset. In the early afternoon the orientation of the CME field flipped to northerly, in line with the earth's field. This blocks the energy transfer and is a big hindrance to the geomagnetic storm and thus the aurora. While it's still possible for the field to flip back southerly, the raw strength is also waning. It's still worth taking a peek, but don't hold your breath.
, Issued at 1230 PM PST Mon Jan 19 2026 (This evening through Tuesday)
Very little change in day to day conditions anticipated through mid week. A ridge of high pressure remains just off of the Pacific coast that will continue to result in temperatures 5-10 degrees above average (up to 15 in the higher terrain). Overnight, we are expecting patch to areas of fog in the North Bay Valleys while tule fog (dense at times) is forecast to advect westward into the interior East Bay Valleys and Delta again either late tonight or into Tuesday morning. If driving or commuting in these areas; be aware of the potential for dense fog and be prepared for sudden changes in visibility, remember to slow down, and use your low beam headlights.
Expecting a slight cool down on Tuesday as more widespread high clouds stream over the region, but only by a few degrees. Where mostly sunny sky conditions prevail, afternoon temperatures will warm into the mid 60s to lower 70s across the Central Coast and low to mid 60s elsewhere. That said, where fog lingers into late morning or early afternoon, expecting temperatures to only reach the upper 50s.
..issued at 1230 PM PST Mon Jan 19 2026 (Tuesday night through next Sunday)
Dry conditions look to persist through much of the extended forecast. An upper level trough will develop over the north central Pacific between Tuesday night and Wednesday. A cut-off low will develop within that trough and move southward just off of the Bay Area/Central Coast, resulting in slightly cooler conditions and cloudier skies through late week. Thus, the greatest potential for rain will be across southern California and along the Santa Lucia Range on Thursday as a deeper plume of moisture advects inland to the south. However there is about a 20% probability of seeing greater than 0.01" and less than a 10% chance of that area seeing 0.10" over that area.
A weak upper level ridge is forecast to develop by this weekend and into early next week. As a result, a slight warming trend is forecast, but not as warm as what we have been the past week. Longer range guidance continues to push back our next potential widespread rainfall. It is not until late January or early February that we forecast widespread rain to return to the region.
(06z TAFS) Issued at 932 PM PST Mon Jan 19 2026
LIFR/IFR vis and cigs are expected for the North Bay terminals as Tule Fog fills in in the vicinity of KAPC and valley fog develops near KSTS. Expect VFR conditions for remaining terminals to the south, including Bay Area terminals.
Vicinity of SFO, VFR is expected to prevail through the forecast period with relatively weak offshore winds prevailing tonight and through the majority of the forecast period Tuesday.
SFO Bridge Approach, Similar SFO.
Monterey Bay Terminals, VFR is expected to prevail with weak but persistent offshore flow through the forecast period.
(tonight through next Sunday) Issued at 932 PM PST Mon Jan 19 2026
Light north/northeasterly breezes will increase later in the week becoming moderate, especially across our northern outer waters. The weak upper level offshore system expected to move southeast through our outer waters this week will result in moderate northwest swell early Wednesday and then again Friday.
Ca, None. PZ, None.
