A Heat Advisory takes effect in The Woodlands on Monday, Sept. 14, with heat index values expected to reach 109 degrees.

The National Weather Service Houston/Galveston office issued the advisory covering Montgomery County and surrounding areas. The Monday advisory runs from 11 a.m. to 6 p.m. CDT. The Woodlands is named among the affected cities.

The advisory also covers Fort Bend, Harris, Grimes, San Jacinto, Walker, Waller, Brazos, Washington and Polk counties, among others.

The combination of high temperatures and humidity creates conditions that can cause heat illness, the NWS warned. The agency urged residents to drink plenty of fluids, stay in air-conditioned spaces, stay out of the sun and wear lightweight, loose-fitting clothing. The NWS also advised limiting strenuous outdoor activity to early morning or evening hours and checking on relatives and neighbors.

Residents should watch for symptoms of heat exhaustion and heat stroke and take action immediately, the agency said.

FOX 26 Houston reported that isolated showers are expected over the next several days, mostly building offshore.

Dr. Leonardo Taarea, a sports medicine physician at Houston Methodist The Woodlands Hospital, offered guidance on recognizing heat illness in an Aug. 9 Woodlands Online article about summer heat safety for high school football players. "Look out for symptoms like cramping, dizziness or lightheadedness, heavy sweating, clammy skin, nausea and vomiting and of course fainting," Taarea said, adding that anyone experiencing those symptoms should seek shade and drink water.

His advice applies broadly. Anyone working, exercising or spending extended time outdoors during the advisory period faces the same risks.

No cooling centers have been announced. Neither The Woodlands Township nor Montgomery County Emergency Management had issued a public statement about the advisory as of Sunday afternoon.

The NWS has not indicated whether the heat threat extends beyond Monday's advisory.