It's extra sunny in Philadelphia this weekend and hot and humid weather is settling over the City of Brotherly Love as tens of thousands of delegates are about to converge on the city for the Democratic National Convention. The heat wave is expected to gain momentum this weekend and peak Monday, the convention's first day, with temperatures possibly hitting 100 degrees, said Mitchell Gaines, meteorologist with the National Weather Service in Mount Holly, New Jersey. Coupled with the considerable amount of humidity, the heat index in the Philadelphia area could be pushed as high as 108 on Monday, Gaines said. Highs in the mid- to upper-90s are expected each day through Wednesday. "The multiple days of excessive heat will greatly affect those who are attending outdoor activities, especially events with large groups of people that are gathering in the direct sun," the weather service said. Officials warned that in urbanized areas such as Center City Philadelphia, even nighttime temperatures may not drop below 80, especially Monday night. Officials also warned of the danger of thunderstorms, which began lashing the city during the late afternoon and evening on Saturday. To protect thousands of demonstrators expected during the July 25 to July 28 DNC, Philadelphia officials said two medic tents and two "misting" tents would be set up and water would be distributed. Medics would also be assigned to take part in marches. Workers preparing for the convention and others in downtown Philadelphia on Saturday afternoon were trying to keep cool.