Summary:
- December was warmer than average over the entire western US and likely helped cement 2024 as one of, if not the warmest years on record in the region, nation, and globally.
- December was wet north and dry south with the divide occurring around the Bay Area.
- Drought conditions have continued to improve in the PNW but have worsened in the southwest.
- A ridge in the west and a trough in the east resulting in the precipitation onslaught in northern California to the PNW likely subsiding into mid-month with temperatures remaining on the mild side. The eastern US is heading into an ice box.
- The forecast for the first month of 2025 is now pointing to the western US likely to see above average temperatures for the month. The January forecast for precipitation continues to show the likelihood of a wetter PNW across the northern states and a drier southern California across the southern states.
- Even though La Niña conditions have been slow to develop and weaker than anticipated, the seasonal forecast is still hanging on to the effects expected from a normal La Niña event. As such, the forecast points to a cooler and wetter winter from northern California into the PNW and cool to near average and dry into southern California
and the southwest. My sense is that the strong negative phase of the PDO is having an outsized influence and that we will end up close to the seasonal forecast for the last half of winter.
