2-meter temperature (F) - Temperatures are displayed by red contours in increments of 5 degrees Fahrenheit (F) starting at 60 degrees F. The minimum threshold of 60 F for display purposes is deemed appropriate because large fires coincide not only with below normal relative humidity, but also with above normal temperatures (Potter, 1996). The SPC fire weather verification scheme uses a minimum temperature threshold of 60 F nationwide as a cutoff for consideration for a Critical/Extremely Critical Fire Weather Area.

High ambient temperatures decrease the moisture content of both live and dead wildland fuels and thus increase their flammability. In addition, high temperatures and direct sunlight preheat the fuels, bringing them closer to their ignition point. Firefighter fatalities have occurred during several fires when record high temperatures were set. For example, on the day on the Mann Gulch Fire in Montana (5 August 1949), a record high temperature was recorded at nearby Helena, Montana (McLean, 1994). All-time-high temperature records were also set in Arizona on 26 June 1990, the day that fatalities occurred on the Dude Fire just below the Mogollon Rim (Whiteman, 2000).

For in depth information on the generation of Nam 2-meter Temperature fields see the following website:
http://www.emc.ncep.noaa.gov/mmb/research/FAQ-eta.html#ETA9