Temperatures will soar Wednesday and Thursday, with high temperatures near 100 and muggy conditions prompting a heat advisory from the National Weather Service.

The advisory will be in effect from noon Wednesday to 8 p.m. Thursday. Temperatures for that time period are expected to be in the high 90s during the day, with a heat index between 100 and 105 degrees. The low at night will be about 70 degrees.

The hot weather means poor air quality and risk of heat exhaustion or heat-related illness.

The Department of Environmental Protection forecast a code orange air quality action day for ozone for all of Pennsylvania Wednesday, warning young children, the elderly and those with respiratory problems such as asthma and emphysema to limit time spent outdoors.

On the pollution scale, a code green signifies good, yellow means moderate, orange represents unhealthy pollution levels for sensitive people and red warns of unhealthy pollution levels for all.

The weather service advises that outside work or activities should be done either early in the morning or in the evening. Wear lightweight or loose-fitting clothing and drink plenty of water, the weather service advises.

People who work outside should take frequent breaks in shaded areas and in air-conditioned environments.

Also, children and pets should not be left in unattended vehicles, as vehicle interiors can reach lethal temperatures within minutes on a hot day, the weather service said.

The heat is expected to break by the weekend, with a slight chance of showers and thunderstorms Thursday night and a low around 74.

There's a chance of showers and thunderstorms Friday, with partly sunny skies and a high near 88.

Friday night will be mostly cloudy with a low around 64.

Saturday is expected to be mostly sunny with a high near 84 and low around 63.

There's a chance of showers and thunderstorms Sunday, with partly sunny skies and a high near 83.

- Staff writer Christina Kauffman contributed to this report Reach Eyana Adah McMillan at emcmillan@yorkdispatch.com.