Is it common practice for the Heat Index to be a degree or two cooler then the Outside Temp reading? <<< I suppose a slight wind does the same thing as a windchill factor even if it is 85F outside.
For lower humidity, yes. At lower humidity the body's perspiration evaporates more readily and therefore the body feels cooler. It's true: at high temps, "it's a dry heat" is more comfortable than a muggy heat. At high humidity, perspiration doesn't evaporate as efficiently, so it feels more uncomfortable.
I am also amazed at how my local TV station will say its 90F outside right now and humidity is 80%, but it feels like a 105F or some large "shock quailifying" number. I have never seen a Heat Index in VWS vary more than 2 or 3 degrees in either direction, for the last 16 months, even in the "doggy-ist" days of summer.
At 80% humidity and 90
oF, the Heat Index is actually 113
oF. Here's a NOAA chart showing Heat Index:
http://www.weather.gov/om/heat/index.shtmlYou can find other charts on the web that give HI at even lower humidities. Heat index and wind chill are definitely an inexact science. In fact, the NWS published a revised wind chill formulation in 2001.
Canada (and perhaps some other countries) uses what is called a "Humidex":
http://www.msc-smc.ec.gc.ca/cd/brochures/humidex_table_e.cfmKevin...
EDIT: Sorry Andrew. We posted nearly simultaneously.