A few weeks ago I was at the YMCA when a man I didn't know approached me and asked if I was responsible for the Ashland temperatures that appeared in the Mail Tribune. I told him I didn't have anything to do with the Tribune, but that the temps there were fairly close to what I usually had.
He said they were nothing like what he got and, when I told him "micro-climates" are the reason, he walked away dissatisfied. But the fact is that the weather can be so different in Southern Oregon within just a few miles that it must drive meteorologists crazy. It's certainly different from the weather in corn-fed (GMO'ed, of course) states like Iowa, Kansas, Nebraska, etc., where the temperatures and precipitation can be the same for a couple of hundred miles.
Although meteorologists give just one forecast for the Rogue Valley (which actually is two discrete geographical entities: the Rogue Valley and the Bear Creek Valley), the differences from west to east can be significant. I'm sure many of you have spent a few hours in "Grants Gass" (sic) where it was cloudy, calm and rainy and got back to Ashland where it was windy, sunny and dry — or were in Phoenix/Talent where it was seriously foggy and got back to Ashland where it was nice and clear.
Even within Ashland there are significant differences. I live on the east side and get around by bicycle. In the winter, I often have to call people on the west side and ask them for the temperature and fog conditions because the east side is usually warmer, drier and windier. These would all be, more or less, micro-climates.
There are even finer gradations that I choose to call nano-climates. These tend to occur in the fall and winter and can be pretty disconcerting for a cyclist. A good example is my street. Quite often it's 5 to 10 degrees colder at the bottom, about a third of a mile away, than it is a my house.
There are often noticeable variations from block to block as I ride through Ashland that I ascribe to small variations in the height of the inversion layer, even when there's little change in altitude. The ScienceWorks Museum weather station is less than 2 miles from my house as the crow flies and less than 200 feet lower, and yet it might as well be in another city, there's so little concurrence in temperature between our two locations, especially in the summer. This would be a nano-climate extraordinaire.
Some differences are hard to explain. Adiabatic cooling rules usually state that the air temperature will drop about 3 degrees for every 1,000 feet of elevation gain, excluding temperature inversions, which tend to be the rule in the winter (particularly in lower lying areas) and result in temperatures rising with increasing altitude.
The Medford airport is at 1,335 feet and my location is at 2,082, so you would expect about 2, maybe 3, degrees difference. But in the summer it's more like 8 to 10 degrees lower for the high (5 to 6 degrees in the winter on non-inversion days). I noticed this subjectively riding home from the orchards in Phoenix to my house and quantified it by putting a thermometer on my bike.
Now, I'm no scientist (to borrow a quote from climate change skeptics), so I don't have an answer as to why this is so, but I'm not complaining. This is one of the reasons I put up with the high cost of living here. It's not just cause "It ain't Medford," it's as much because "It's the climate" — a slogan much more suitable for Ashland than it ever was for Grants Gass (sic).
Weather or Not by Ashland weather statistician Doyle Hirsch appears periodically.