It's going to be another hot day in Delaware as a heat wave will cause a heat advisory in Delaware with the heat index reaching over 100 degrees in most of the state.
With the heat, severe thunderstorms could also be possible.
Here's the latest weather forecast:
When will Delaware cool off? Here's when the heat wave will break
Delaware weather forecast: Heat advisory for Delaware
A heat advisory will in effect for northern Delaware, portions of New Jersey and southeastern Pennsylvania on July 29 as temperatures continue to rise through July 30, according to the National Weather Service in Mount Holly, New Jersey.
The forecast calls for very hot and humid conditions with heat indices between 100 to 105 degrees will lead to an increased risk of heat related illnesses, according to the NWS.
Conditions will lead to an increased risk of heat related illnesses.
Here's what it could feel like in Delaware on July 29 with the heat index:
Wilmington: 103 degrees
Dover: 102 degrees
Bethany Beach: 90 degrees
Severe thunderstorms possible
Along with the hot and humid conditions, there will be a possibility of isolated severe thunderstorms with locally damaging wind gusts, resulting in tree damage and power outages.
Storms are possible on July 30 for areas along and northwest of the Interstate 95 corridor, according to the NWS.
During the afternoon and into the evening of July 31, showers and thunderstorms with locally heavy rainfall could lead to flash flooding of urbanized and poor drainage areas, small streams and creeks in Delaware, New Jersey, southeastern Pennsylvania and northeastern Maryland. Flooding could result in road closures.
The AQI determines how clean or polluted air is and what associated health effects might be a concern.
Here is how to read the categories for the AQI index:
Air quality alert for Delaware
The hot and humid weather will cause an air quality alert for all of Delaware on July 29, according to the state Department of Natural Resources and Environmental Control.
The alert is due to a morning temperature inversion which will trap pollutants near the surface according to the DNREC. In addition, calm to light westerly winds will reduce dispersion and gradually transport regional pollutants into Delaware, the agency said.
Mostly sunny skies and high temperatures in the upper-90s will enhance ozone production, causing air quality index levels to be unhealthy for sensitive groups as the as ozone index reaches 101.
While increasing south-southwesterly winds will aid dispersion with partly cloudy skies hindering ozone production, mostly sunny skies and highs in the mid-90s will continue to support ozone development and cause moderate ozone levels for July 30.
Good: 0 to 50. Air quality is satisfactory and pollutants pose no risk
Moderate: 51 to 100. Air quality is acceptable. However, there may be a risk for some people, particularly those who are unusually sensitive to air pollution.
Unhealthy for Sensitive Groups: 101 to 150 Members of sensitive groups may experience health effects. The general public is less likely to be affected.
Unhealthy: 151 to 200. Some members of the general public may experience health effects; members of sensitive groups may experience more serious health effects.
Very Unhealthy: 201 to 300. Health alert: The risk of health effects is increased for everyone.
Hazardous: 301 and higher. Health warning of emergency conditions; everyone is more likely to be affected.
What is an excessive heat warning?
There are four advisories for heat, according to the National Weather Service:
Excessive heat outlooks are issued when there is a potential for excessive heat within the next three to seven days. It gives people time to prepare for the weather.
Heat advisory: A heat advisory is issued within 12 hours of extreme heat conditions. Typically, the heat index will be above 100 degrees and the nighttime air temperature will not drop below 75 degrees. However, the criteria vary by area.
Excessive heat watch: A heat watch is issued when conditions are favorable for excessive heat in the next 24 to 72 hours.
Excessive heat warning: The warning is issued within 12 hours of the onset of hazardous heat conditions.
What is the heat index?
According to the National Weather Service, the heat index represents the temperature that feels like it to the human body when relative humidity is combined with air temperature.
When the body sweats, the perspiration evaporates, cooling the body. When the humidity is high, the sweat doesn't evaporate as quickly and the body doesn't cool itself as well. Therefore, the body feels warmer. The heat index represents the heat you're feeling outside.
There are four classifications for heat index, according to the National Weather Service:
Caution: When the heat index is 80-90 degrees, prolonged exposure to heat and physical activity can cause the body to feel fatigued.
Extreme caution: When the heat index is 90-103 degrees, the body may feel heat stroke, heat cramps and heat exhaustion with prolonged exposure and physical activity.
Danger: When the heat index is 103-124 degrees, heat cramps or heat exhaustion are likely, and heat stroke is possible with prolonged exposure and physical activity.
Extreme danger: When the heat index is 125 degrees or higher, heat stroke is likely.
Greg Giesen contributed to this story.
This article originally appeared on Delaware News Journal: Delaware weather: Heat advisory, thunderstorms , flash flood this week
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