December ends with rainy weekend

Water stands in farm fields around La Conner at the start of the new year. Almost half of December’s rain, 1.85 inches, came the last weekend, Dec. 28-30. The month’s 3.79 inches was about 10 percent above the 3.35 average rainfall for the 17 years of data this century.

The first eight days were dry, as was half the month, 15 days, total. Under one-tenth inch fell seven days. Rainfall was primarily on Dec. 9-14 and 28-30.

There wasn’t an apparent pattern to the month’s precipitation.

While snow is seen increasingly lower on the Cascade foothills, no snow fell in greater La Conner. Temperatures on rain days were above freezing.

Between three and four inches of rain has fallen nine of the 17 Decembers reported. Two years, 2009 and 2011, had 1.25 inches of rain. The most rain, seven inches, came in 2015. For the century, there doesn’t seem to be a pattern to rainfall totals.

2018 rain shadows

Dividing 2018 into a winter wet season of January-April, a dry season of May-August and a fall wet season of September-December, 18.1 inches of rain fell through April; 2.14 inches came May-August; and 11.7 inches the last four months. Fifty-seven percent of the year’s rain came at the start of 2018 and another 37 percent in the fall.

July’s 0.04 inch was by far the least amount of rain. February’s 5.78 inches of rain was the highest by an inch. Less than three inches of rain fell in each of the “wet” months of March, September and October.

Because data are missing in different years, it is not possible to make an analysis for annual precipitation across the century’s decades.

Measurements and data are at Washington State University’s Mount Vernon weather station on Memorial Highway.