By Lauren Casey

PHILADELPHIA (CBS) — The second heat wave of the season has commenced. A heat wave is generally defined as three or more consecutive days of 90 degree heat.

The high temperature in Philadelphia once again crossed the 90 degree threshold Tuesday after a two-day reprieve. High temperatures are forecast to remain in the 90s through the July 4th holiday and into the weekend.

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Highs in the low-90s, in combination with increased humidity levels on Wednesday, may force heat index values into the upper 90s. We’ll contend with the most humid of conditions on Friday and Saturday when heat indices could soar into the triple digits.

Stay tuned to the evolving forecast and beware of any excessive heat watches or warnings that may be issued.

The New Jersey Department of Environmental Protection has issued a code orange air quality alert for all of southern New Jersey on Wednesday. A code orange means that air pollution concentrations may be unhealthy for sensitive groups, including children, people with asthma, heart disease or other lung diseases, and the elderly.

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During this week’s heat wave, be sure to take it easy and reduce strenuous activities, drink plenty of water, spend time indoors in the air conditioning, and NEVER leave children or pets in parked vehicles.

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