* WHAT...Temperatures up to 99 expected. * WHERE...Guadalupe Mountains of west Texas and Southeast New Mexico, Chinati Mountains, and Davis Mountains. * WHEN...From noon MDT /1 PM CDT/ Monday to 8 PM MDT /9 PM CDT/ Tuesday. * IMPACTS...Hot temperatures may cause heat illnesses. Extreme heat will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities.