I just finished a truncated tour of the Pacific Coast (Oregon to N. Cal) and got exactly two days of those famous tailwinds. Every other day was a head wind, or calm. And I got rained on about 30% of the time. Riding it in Jan/Feb is about the last thing I'd want to do, but to each his/her own.
Personally, I'd much rather plan a route around AZ that time of year. My first tour took place in AZ during early February, and the weather was great (60s to 70s), with the exception of one rather nasty storm that lasted one day.
The following is a quote from weatherspark.com (reports), describing a typical January 31st in Astoria, OR. http://weatherspark.com/#!reports;a=USA/OR/Astoria;tr=1/31
This report describes the average weather conditions at the Port Of Astoria Airport weather station on a generic January 31. It is based on a statistical analysis of the historical records from 1974 to 2011. Earlier records are either unavailable or have been deemed to be too unreliable to include in this analysis.
The temperature typically varies from 40°F to 48°F and is rarely below 31°F or above 55°F. The coolest hours of the day are from 11pm to 9am with the coldest at 7am, at which time the temperature is below 46°F three days out of four. The warmest hours of the day are from noon to 5pm with the hottest at 3pm, at which time the temperature is above 45°F three days out of four. The day has gained half its heat by 11am and lost it again by 7pm.
The sky is typically overcast with 99% of the sky covered. The sky is 93% covered (mostly cloudy) or cloudier three days out of five. There is little variation in the cloud coverage over the course of the day.
There is a 69% chance that precipitation will be observed at some point during the day. The average liquid-equivalent quantity of precipitation is 0.28 inches. Among only those days for which there is at least some precipitation, the average is 0.40 inches and the total rarely exceeds 0.85 inches. When precipitation does occur it is most often in the form of moderate rain (49% of days with precipitation have at worst moderate rain), slight rain (31% of days with precipitation have at worst slight rain), heavy rain (7% of days with precipitation have at worst heavy rain), and slight snow (6% of days with precipitation have at worst slight snow). Precipitation is observed with more or less equal probability throughout the day.
The wind speed is 8 mph on average and is rarely outside the range 2 mph to 16 mph. The wind speed does not vary substantially during the course of the day. The wind is most often out of the east (31% of the time). The wind is least often out of the north west (3% of the time) and north (4% of the time).