Morning frost ends Inland NW growing season

The first widespread frost of the fall season settled over much of the Inland Northwest this morning, ending what had been a longer-than-normal growing season. Frost-tender plants and vegetables succumbed to temperatures in the upper 20s to about 30, according to reports at dawn. With a few clouds in the region, there is a 10 percent chance of a snow shower this morning. Air quality slipped into the moderately polluted category this morning, but has improved with the sun heating the air and lifting a cold-air inversion that has held pollutants near the ground. The air forecast is for moderate pollution to continue again on Wednesday. National Weather Service forecasters said the cold air will be followed today by sunshine and highs near 50. Cool and dry air from Canada has migrated into the region, allowing for the rapid cooling under cloudless skies at night. Freezing temperatures are likely in each of the next two nights. At 7 a.m., it was 30 at Spokane International Airport and Felts Field near Millwood, 27 in Coeur d’Alene, 28 in Pullman and 22 in Deer Park. The average date of the first frost in Spokane is Oct. 7, making this year’s growing season more than two weeks longer than normal. For growers, it has helped make up for a cool spring and slow start for most heat-loving plants. A freeze warning was in effect today for growing areas of south-central and southeast Washington, including the Columbia, Walla Walla and Yakima valleys. Pasco was 28 degrees at 8 a.m. Grape crops along Lake Roosevelt on the Columbia River were spared freezing temperatures because the lake warms the air with its moisture, creating fog, said vineyard manager and wine maker Michael Haig, of Whitestone Vineyard and Winery north of Creston. The temperature dropped to 35 overnight, he said. Highs through the week will be in the lower 50s with lows at night in the lower 30s. The chance of showers returns to the forecast on Friday.