Heat warnings were in effect Tuesday from Southern California to Mississippi as record-breaking temperatures swept across the nation’s southern tier with little relief in sight.
The National Weather Service said new highs were forecast from the Four Corners states and Texas to the Lower Mississippi Valley and South Florida.
Phoenix was leading the pack. The “Valley of the Sun” is accustomed to extreme summer conditions, but the mercury reached 114 on Sunday and 116 on Monday. AccuWeather forecast temperatures to climb above 110 each day through at least the end of the weekend. The forecast high of 116 on Tuesday would break the record high for the date set in 1989. Thursday’s expected high of 117 would break a record last set in 1978.
For eight days in a row, low temperatures have not dipped below 90 in Phoenix.
The desert Southwest and Texas can expect consistent daytime highs in the triple digits, while temperatures in the Gulf Coast and mid-South should reach the mid- to upper 90s – with humidity combining to push the heat index to 105-115, according to the National Weather Service. Despite a recent weak cold front passing, the Northeast and mid-Atlantic will also continue to see hot and humid conditions through Tuesday.
The silver lining: Air quality that has been hovering in the danger zone in parts of the U.S. for days was improving Tuesday. The only U.S. city in the “unhealthy for sensitive groups” zone was Washington D.C., according to iqair.com.
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Air quality alerts emerge throughout Northern High Plains, Midwest, Great Lakes and Northeast
Direct smoke from the Canadian wildfires will continue to reach the Lower 48 on Tuesday, but air quality was improving. Air quality alerts had been issued Monday for much of the northern High Plains, the Midwest, Great Lakes, central Tennessee and North Carolina and into the Northeast, according to the weather services. Smoke concentrations appeared to be clearing over parts of the U.S. on Tuesday, but the respite could be brief and subject to the vagaries of the winds. Canada continues to witness the nation’s most extensive wildfires on record − an area about the size of Kentucky is on fire.
Tropical Storm Calvin weakening before reaching Hawaii
Tropical Storm Calvin, now downgraded from a hurricane, will further weaken as it approaches the island of Hawaii, the weather service reports. The state’s largest island has tropical storm watches in effect late Tuesday until Wednesday when the system is expected to become a tropical depression.
The area can expect heavy rainfall locally with about 4-7 inches on windward slopes and possible rough waves. Maui and Hawaii counties are under a flood watch from Tuesday evening until Wednesday afternoon, according to Hawaii News Now.
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Numerous thunderstorms to engulf parts of Midwest and East
Heavy and excessive rainfall can be expected over the Northeast as a cold front comes from the west Tuesday.
Portions of the Ohio Valley have higher risks of excessive rainfall on both Tuesday and Wednesday. While the Plains and Ohio Valley have lower chances of severe weather on Wednesday, residents near the Illinois/Missouri border can expect some of the heaviest rainfall, according to the weather service.
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