We're trying to decide if we want to hike tomorrow. Well, we know we want to, but we don't know if it will be too hot. We were planning to do a fairly difficult hike and the high tomorrow is forecast to be somewhere between 84 and 90. That's kind of a wide range to plan for, considering it's only a day away.

But, the weather here is complicated. Most forecasts for Seattle have the weather around 85 degrees. But, we're actually hiking just 30 miles east of here, which could be cooler or several degrees warmer than Seattle (90ºF according to one forecast). And on the coast, less than 100 miles due west of Seattle, the forecast high for Friday is only 70º. East of Seattle, past the Cascade mountain range, the forecast high for Friday is around 98º. So, over 190 miles or so, the forecast high varies by 28 degrees.

The water and mountains cause amazing weather variability in weather in other seasons as well. The coast (near an actual rainforest in Olympic National Park) gets more than 12 inches of rain per month for 5 months out of the year. It's so much rain that the Weather.com bar graph can't accurately fit the full bars.

The rain in "rainy Seattle" tops out at 6 inches on average in the month of December. But North Bend, just 30 miles east of the city and part of the Cascade foothills gets 50% more precipitation every month of the year. You could say that Seattle is the driest place around. Unless you count Sequim, just 50 miles directly northwest of Seattle but in a natural rain shadow provided by the Olympic mountains, which gets about 16 inches of rain per year compared to Seattle's 38 inches, which is still more than the 9 inches of precip that falls in Wenatchee just over the Cascade mountains. So, over the same 190 miles between Wenatchee and the coast, the precipitation varies by more than an order of magnitude (113" on the coast, 9" in Wenatchee).

In the winter, all of that precipitation is snow on the mountains. But at slightly lower elevations it might be snow or it might be rain. In December when there was that crazy snowstorm in Seattle, though the city streets had an inch or so of ice, my coworkers who lived on the Eastside had feet of snow around their homes.

I remember on the local weather in Texas, meteorologists would tell the weather nearby: "It's 90 in Denison, 91 in Fort Worth, and 89 in Dallas." And I thought that was stupid because there was never a big variation. But here, there is a big variation because the mountains and the water have a big affect on weather patterns. So, though I'd like to know if it will be cool enough to hike tomorrow, I can understand why forecasting here tends to be varied and inaccurate.