High‑Pressure Ridge Keeps Western Washington Dry A strong ridge of high pressure dominates the West Coast, locking in clear skies and suppressing precipitation through mid‑week and into the weekend, extending the region’s longest dry spell since September [1][2]. Sunshine increases each day while clouds remain stubborn at times, maintaining daytime highs near seasonal levels in the upper‑40s to low‑50s [1][2]. The ridge also supports unusually warm January conditions, with record‑tying 58 °F at Sea‑Tac and 57 °F in Olympia [2].

Temperatures Reach Seasonal and Record Levels Daytime highs hover in the upper‑40s to low‑50s across western Washington, while night‑time lows plunge into the mid‑20s in the South Sound, fostering patchy fog and frost overnight [1]. An inversion traps cooler air near the surface, allowing Paradise on Mount Rainier to hit 58 °F despite colder air aloft [2]. The warm air aloft contributes to the overall January warmth that underpins the persistent dry pattern [2].

Rain and Snow Expected Later in the Week The ridge is forecast to weaken by Friday, permitting weak northwest disturbances to bring rain into the region [1]. Snow levels are projected to fall to around 2,000 ft as colder air moves in, though another source cites snow levels near 12,000 ft, highlighting a discrepancy in model outputs [1][2]. High temperatures will remain in the 40s during the rain, signaling the end of the current dry spell [1].

Frost, Fog, and Outdoor Event Outlook Patchy fog and frost are likely Sunday night into Monday, clearing by late morning [1]. Forecasters anticipate mostly sunny conditions for the Seahawks game on Saturday, with temperatures dropping from the mid‑upper 40s to the low‑mid 40s by game’s end, supporting tailgating plans [2]. The unsettled pattern beyond mid‑week suggests increasing cloud cover and additional rain chances later in the week [1][2].