Arizona. Excessive Heat Warnings are in effect for many cities in the region as temperatures are expected to rise this weekend. Channel 4's Kumasi Aaron spoke to the National Weather Service today, about why the warnings are so important. 3 3 3 This weekend the south west is getting ready for even more scorching weather.Temps in parts of Arizona and Calfornia are forcasted to rise to the 120's. And in parts of Nevada, the temperature is forecast to hit 115.TAKE NAT: 063731-33 Excessive heat warning 113-118 Dr. Pete Wolf with the National Weather Service Jacksonville says that's why the agency issued a heat warning. DR. PETE WOLF/NATIONA L WEATHER SERVICE JACKSONVILLE SCIENCE AND OPERATIONS OFFICER 06:48:08-18 "It's typical for that area to be on the hundreds this time of year now. 110 120 it gets to be a little more extreme especially when it doesn't drop below 90s or upper 80s Dr. Wolf says the regiona high pressure dome that's blocking cooler air from the Pacific Northwest is to blame and it's not expected to leave until early next week. Another factor, the jet stream, which also affects other parts of the country. DR. PETE WOLF/NATIONAL WEATHER SERVICE JACKSONVILLE SCIENCE AND OPERATIONS OFFICER 06:46:34-43 "Then the jet dives over our area the eastern United States and allows cooler air over New England and somewhat stormier weather for us here in Florida. Stormier weather and much cooler temperatures than our neighbors to the west. DR. PETE WOLF/NATIONAL WEATHER SERVICE JACKSONVILLE SCIENCE AND OPERATIONS OFFICER 06:48:47-49:04 That's one of the benefits of Jacksonville Florida even though we get hot in the summertime by living near cooler water that difference of pressure brings a sea breeze inland KUMASI LKL TAG: Just to put this in prospective the temperatures in the southwest are higher than Jacksonville's all time high which was 104 degrees back in July of 1879 Kumasi Aaron Channel 4 The Local Station.