Meteorologists said they have watched the La Niña strengthen through the month of October, although it won't really start affecting the weather in the Pacific Northwest until January. by: ... An unsettled weather pattern is hanging around the Pacific Ocean off the coast of Oregon to start the week. Home > Graphical Forecasts > Pacific Northwest: This graphical forecast page is planned to be replaced by the map viewer now operationally available at digital.weather.gov. The best weather for long-distance trips on the PNT generally occurs between mid-June and mid-September. The Pacific Northwest can expect temperatures to be near-average or slightly warmer, with a trend toward slightly below-average conditions in ⦠The Monthly Rainfall Totals are rainfall data collected from the U.S.-Affiliated Pacific Islands (USAPI).Providing up-to-date information on climate variability related to the ENSO climate cycle for their respectable regions. Trails are typically snow free from all but the highest elevation areas by July. The soggy weather is the result of a stream of Pacific moisture stretching several thousand miles into the central Pacific. nSlightly below-average temperatures are likely statewide, especially early in the period. Black History Month; ... 78.4% of Pacific Northwest covered in snow Weather. Over the past month, SSTs have warmed in the western Pacific with little change for the rest of the basin. ENSO forecast models favor a return to neutral conditions by April-May-June with a ⦠This set-up, called an âatmospheric river,â brings days of heavy rain into the Pacific Northwest while producing snow over the highest elevations of ⦠This creates a narrow weather window compared to other National Scenic Trails. They all had La Niña conditions in the tropical Pacific Ocean. Forecast Highlights nThe analog years (1971, 1996, & 2008) are unchanged from last month. The principal El Niño index, NINO 3.4, has risen to -0.65 indicating a weak La Nina. nPrecipitation should be mostly near average, with the best chances for above-average precipitation west and north. January What is typically the coldest month could be ⦠SEATTLE (AP) â A major storm carrying high winds, drenching rain and heavy snow is headed for the Pacific Northwest, according to weather ⦠Warmer than average temperatures are most likely from the Southern Plains and Southwest into the Pacific Northwest. National Weather Service National Centers for Environmental Prediction NOAA Center for Weather and Climate Prediction (NCWCP) Ocean Prediction Center 5830 University Research Court College Park, Maryland 20740-3818 Phone: 301-683-1520 Fax: 301-683-1501 (SDM), 301-683-1545 (back office-administrative) OPC Email Feedback The 1,200 mile Pacific Northwest Trail has an east-west orientation.