...HEAT ADVISORY NOW IN EFFECT UNTIL 10 AM EDT MONDAY... ...EXTREME HEAT WARNING IN EFFECT FROM 10 AM TO 8 PM EDT MONDAY... ...HEAT ADVISORY IN EFFECT FROM 8 PM MONDAY TO 8 PM EDT WEDNESDAY... * WHAT...For the first Heat Advisory, heat index values up to 105. For the Extreme Heat Warning, dangerously hot conditions with heat index values up to 107 expected. For the second Heat Advisory, heat index values up to 102 expected. * WHERE...Columbia, Juniata, Mifflin, Montour, Northumberland, Schuylkill, Snyder, Southern Lycoming, and Union Counties. * WHEN...For the first Heat Advisory, until 10 AM EDT Monday. For the Extreme Heat Warning, from 10 AM to 8 PM EDT Monday. For the second Heat Advisory, from 8 PM Monday to 8 PM EDT Wednesday. * IMPACTS...Heat related illnesses increase significantly during extreme heat and high humidity events. Hot temperatures and high humidity may cause heat illness. * ADDITIONAL DETAILS...The highest heat index will occur in the urban valley locations. Temperatures in the 70s overnight will provide little if any relief. PRECAUTIONARY/PREPAREDNESS ACTIONS... Drink plenty of fluids, stay out of the sun, and stay in an air-conditioned room. Check up on relatives and neighbors, and provide pets with adequate water and shelter from the sun. Extreme Heat can be life-threatening among at-risk populations, such as children, the elderly, and those with pre-existing health conditions. &&