The National Weather Service has issued a heat advisory that will be in effect from 11 a.m. to 8 p.m. Monday in Livingston and Orleans counties.

Heat index values – a measure of how the temperature feels – in the upper 90s are expected.

The advisory also includes Monroe, Ontario, Niagara, Wayne, northern Cayuga and Oswego counties.

High temperatures near 90 degrees are forecast along with dewpoints in the lower 70s, according to the National Weather Service.

“Highest dewpoints are likely along the southern Lake Ontario lake breeze (which will not drop too far southward due to a stiff southwesterly gradient wind). The combination of heat, air temperatures in the mid 80s to lower 90s, and high dewpoints will send apparent temperatures above 95F, meeting heat advisory criteria for the areas south of Lake Ontario, from Niagara County to Oswego and inland across the Genesee Valley/northern Finger Lakes region,” the Weather Service said in a forecast discussion on Sunday.

The heat advisory does not include Genesee or Wyoming counties, where high temperatures are forecast near 85 degrees on Monday.

Normal high temperatures for the region in late July are around 81 degrees, according to historical data from the Weather Service.

There is also a marginal risk for severe thunderstorms Monday afternoon into Monday evening across all of Western New York and the Finger Lakes, including the four-county GLOW region. The primary risk would be damaging wind gusts, in addition to tropical like downpours and cloud to ground lightning strikes, the Weather Service said.

The combination of hot temperatures and high humidity can create a dangerous situation in which heat illnesses are possible. Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances.

Know the signs and symptoms of heat exhaustion and heat stroke. Muscle cramping is usually the first sign of heat-related illnesses (heat exhaustion or heat stroke).

Symptoms of heat exhaustion include nausea, vomiting, cold/pale/clammy skin, heavy sweating, fast and weak pulse, weakness or fainting and fast and shallow breathing. Victims of this illness should be moved to a cool place, be cooled using any method available such as ice packs; cool, wet cloths, or by applying water to the body, and sip on water. If a victim is continuously vomiting or loses consciousness, call 911 or your local emergency number immediately.

If heat exhaustion is not treated it may progress to heat stroke.

Symptoms of heat stroke include hot body temperature, hot/red/dry/moist skin, rapid and strong pulse and possible unconsciousness. Victims of this illness should be treated in the same ways as those with heat exhaustion

Anyone overcome by heat should be moved to a cool and shaded location.

Take extra precautions if you work or spend time outside. When possible reschedule strenuous activities to early morning or evening.

Wear lightweight and loose fitting clothing when possible. To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments.

Temperatures are expected to return to the low 80s on Tuesday.

Johnson Newspapers 7.1