The operator of the electric grid that serves most of Texas has declared an energy conservation emergency as temperatures across much of the state approached or exceeded 100 degrees (38 Celsius).
The Energy Reliability Council of Texas appealed to all of the state's consumers of electric power to limit and reduce their usage during the peak demand hours of 3 to 7 p.m. Tuesday after reserve capacity fell below 2,300 megawatts.
No rotating power outages were immediately reported.
ERCOT suggests setting thermostats 2 to 3 degrees higher, set pool pumps to shut off from 4 to 6 p.m., turn off and unplug nonessential lights and appliances, and avoid using large appliances such as ovens and washing machines during peak hours.
A megawatt is about enough electricity to power roughly 200 homes running air conditioners during hot weather.
The Dallas Zoo prepared for large crowds Tuesday during $1 admission day even as forecasters predicted triple-digit temperatures and issued a heat advisory.
Zoo spokeswoman Chelsey Norris says a typical summer weekday would attract 2,000 guests. Norris says a Dallas Zoo dollar admission day in July drew more than 30,000 visitors, with temperatures in the 90s.
Norris advised visitors Tuesday to be prepared for hot weather by using sunscreen and drinking lots of water.
Misting tents were set up throughout the Dallas Zoo to provide visitors with another way to cool down.
Norris says zoo personnel closely monitor the animals and move them to cooler indoor areas as needed.
She says elephants would be soaked with water cannons and offered frozen ice treats.
Forecasters say most of the South - from Texas to parts of South Carolina - will be under heat advisories and warnings as temperatures will feel as high as 117 degrees (47 Celsius).
The most intense heat Tuesday is expected in Mississippi, Arkansas, Louisiana, and Alabama; and in areas near Memphis, Tennessee.
The warnings come one day after the temperature and humidity combined for a Monday heat index of 121 degrees (49.4 Celsius) in Clarksdale, Mississippi. It was only a few degrees cooler in West Memphis, Arkansas.
In Alabama, the highest reported heat indexes Monday were 112 degrees (44.4 Celsius) in Florence, Tuscumbia and Gurley.
Forecasters say the heat index is what the temperature actually feels like.
A break from the heat is expected by Wednesday as a front pushes through.
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