If people know nothing else about Lewis and Clark's winter on the lower Columbia, they probably know about the weather and that legendary, endless rain.
Retired meteorologist George Miller, who made a career forecasting sun, rain and snow for the National Weather Service, takes a look back in time in his new book, "Lewis and Clark's Northwest Journey - 'Weather Disagreeable!'"
Miller combed the explorers' journals to piece together the likely weather patterns that brought the rain, fog, wind, snow and occasional sunshine to the party as it waited out the winter at Fort Clatsop.
"People are always saying how terrible the weather was that winter," he said. "I thought 'let's see if it was really as bad as they think it was.'"
His conclusion? The Corps of Discovery probably endured a winter that was wetter and stormier than average, but the number of rainy days was right around average.
Weather and the seemingly endless rain is a constant topic in the explorers' journals - "There is more wet weather on this coast than I ever knew in any other place," Sgt. Patrick Gass wrote on Dec. 5. Miller thinks it wasn't necessarily the volume of precipitation that got to the men but the fact that it was wet for so many days in a row, something not as common with East Coast winters.
Based on the explorers' journals, Miller counts 124 "rain days" between Nov. 1, 1805 and March 31, 1806. Add four days of snow the party also recorded, and you get 128 days of precipitation during that 151-day period.
Astoria weather station records for the same dates in 2003-04 show 116 days of measurable rain, with another 11 days with at least a trace of precipitation, Miller writes, even though the overall rainfall for that period was below normal.
What was out of the ordinary that winter two centuries ago, and is less well-known today, was the unusually frigid weather the party endured for two weeks in January and February, when several inches of snow fell and the temperature dropped to well below freezing. The nearby Netul River even froze over in several places, making canoe travel difficult for the hunting parties.
From the journal entries, Miller guesses that the region was hit, probably two or three times, with strong, cold arctic blasts from Canada or Alaska, thanks to an unusual change in course by the jet stream. Looking back over Astoria weather records, Miller said he can't find a similar stretch of cold weather comparable to what the explorers described. "That was unprecedented," he said.
The party's last remaining thermometer had been broken in Idaho and the explorers had to estimate the daily temperatures, but Miller is confident that they were close to accurate in their figures, which ranged from a high of 55 to a low of 15 above zero during the cold snap. Without a thermometer, Lewis buttressed his estimates with various observations, such as how the water in a container left out all night "feized the whole thickness."
Miller is impressed with Lewis' observations, for example how he noted that eastern winds from the land brought generally colder, clearer weather, while the rain and storms blew in mostly from the southwest - exactly the patterns that shape the coast's winter weather.