Skated 15.75 miles in 1:08:01 (13.9 mph), HR 71%, temp 42-40.* Tonight's skate was significant because the temperature was similar to the average low temperature on the date I've been considering for the WR attempt (47 degrees and September 5-6). I was interested in whether I could skate comfortably at this temperature in clothes that I could change without removing my jersey or skates, and that weren't too cumbersome.
The answer: a quite definite NO. I wore light stretchy gloves, arm warmers, a bandanna under my helmet, and a pair of sweat pants I cut off just below the knee -- and I was uncomfortably cold the entire skate. By the time I finished, my toes were numb and my arms and fingers were stiff and cold. I had planned to skate for 2 hours but I saw no point in continuing the misery. I have skated in much colder temps than this, but only with a warm undershirt, heavier gloves, and skate covers, none of which I want to contend with during the WR attempt.
It appears that temperature will be a problem. There is no 24-hour time period at any point of the year in Colorado with acceptable temperatures at both the high and low ends. Our dry, thin air doesn't hold heat well, so even hot summer days can be followed by cool nights. For example, if I go for the record on August 8-9, the average high and low are 88 (warm enough to affect performance) and 54 (cool enough to need arm warmers at nighttime). There is no way to get around this without a radical change in location, so it appears I have a choice to make: do I want to face the heat or the cold?
* Explanatory note for Canadian readers: temperatures on this blog are given in "degrees Fahrenheit," -- much like the "degrees Kelvin" you use, except better. The conversion is quite simple: 1 degree Fahrenheit equals 2.54 degrees Kelvin, so 42 degrees Fahrenheit equals... uh... divide? multiply? Anyway, if you can find one of those banks with the signs that show the temperature in both scales, just wait around till it says "42F" and the answer will appear shortly thereafter.