History shows Oregon should have sunny eclipse day

Visitors from around the world will flock to Oregon to be first in line to see the solar eclipse on Aug. 21, but given the state’s reputation for clouds and rainfall – will there be anything to see?

Time will tell, experts say, but Oregon is usually delightful in the summer, and whoever scheduled this eclipse picked a good date. August is just about the least likely time to experience inclement weather in the Beaver state.

“If you were going to go to Las Vegas or Atlantic City and put down a bet on which location in the United States will have good weather for the eclipse – Oregon would be a great choice,” said Kathie Dello, deputy director of the Oregon Climate Service at Oregon State University. “The average high temperature on Aug. 21 is 82 degrees and it just doesn’t rain very often here in August.”

OSU is the state’s largest university and located in Corvallis, which is on the eclipse’s path of totality. The university is expecting to host thousands of visitors for the eclipse and numerous events have been scheduled.

The city hasn’t experienced measurable rainfall in the past six weeks, Dello said. Whether that streak continues remains to be seen.

History is on the side of a sunny Aug. 21 in the state, statistics show. It hasn’t rained in Corvallis on Aug. 21 since 2008, when .02 inches fell, which, coincidentally, is the average for Aug. 21 when measured over more than a century. Most of that precipitation occurred during a rare storm in 1979 when 1.42 inches of rain pelted the Willamette Valley. Take away that one day, and it’s practically desert conditions in Corvallis on Aug. 21.

In fact, the average rainfall for the entire month of August in Corvallis and much of western and eastern Oregon is about a half an inch.

“The biggest threat during the summer months is low-level marine stratus sneaking its way into the valley,” Dello said. “But the chance of that is weighted more toward June than it is July, August or September. In Eastern Oregon sites like Madras – which also is on the path of totality – the biggest threat to cloudy skies in August would be an afternoon thunder shower. But the eclipse will be over by lunch.”

Scientists in Oregon and nationally will also be watching the eclipse to see what happens to temperatures when the sun disappears in mid-morning – and the effect of that on the rest of the day, according to Philip Mote, director of the Oregon Climate Change Research Institute at Oregon State.

“Temperatures on a summer day in Oregon typically rise quickly between 9 a.m. and noon, but on Aug. 21, the shrinking sun from 9 to 10:15 a.m. could actually make the day get cooler during that period,” Mote said. “Once the shadow of the moon starts to pass, temperatures will resume their rise, but the eclipse will probably end up affecting the daytime high by several degrees.

“If it’s cloudy, the effects of the eclipse on the hour-by-hour temperatures will be less.”

Researchers and “citizen scientists” around the country will be recording temperatures and sharing them with the National Aeronautics and Atmospheric Administration (NASA). To learn more, go to https://go.nasa.gov/2tBJyxH.

Here are some Aug. 21 weather statistics for various Oregon locations on the path of totality:

Corvallis: Average high and low temperatures of 82/51, with a record high of 99 degrees in 1942, and a record low of 37 degrees in 1973. The average precipitation for Aug. 21 is .02 inches, with a record that day of 1.42 inches in 1979. Newport: Average high and low temperatures of 65/52 degrees, with a record high of 74 (1997) and record low of 40 (1987). Average precipitation is .02 inches, with a record of .59 inches in 1971. Madras: Average high and low temperatures of 84/45 degrees, with a record high of 100 (2009) and a record low of 30 (1933). Average precipitation is .01 inches, with a record of .26 inches in 1979. John Day: Average high and low temperatures of 87/48 degrees, with a record high of 103 (2009) and a record low of 36 (1950). Average precipitation is .02 inches, with a record of .50 inches in 1954. Baker City: Average high and low temperatures of 83/44, with a record high of 98 (2005) and a record low of 35 (1966). Average precipitation is .02 inches, with a record of .58 inches in 1959.