Chris, I contacted Ambient and recieved this response:
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Wind chill requires two things:
1. Temperature < 40 degF
2. Wind > 4 mph
<snip>
Ed
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I monitored my machine via the ambient.net dashboard the the above criteria proved correct.
Yeah, i had contacted them and that's what i was told.
Earlier in the week, we had some cold windy days. I sat and watched my live data several times. It would occasionally change the wind chill number briefly. I think the problem is the location of my weather station. My wind speed and direction is not as accurate as it should be. I live in a subdivision with houses around. They are spaced out pretty far, but i think it still affects my readings. The fences everyone has probably creates some turbulence on the wind vane as well. The only way to fix that is to mount it way up on the roof, which i am not going to do.