A summer World Cup in the United States was bound to be affected by heat, but temperatures for some of this week’s knockout round games could prove dangerous for players and fans. A threatening heat dome will engulf the central and eastern U.S. this week with heat index temperatures — which combine air temperature with humidity — soaring into the triple-digits in some areas.

Heat-Related Dangers

Conditions will bring above-average temperatures to World Cup host cities such as Boston, Philadelphia, and Kansas City, Missouri, all of which have open-air stadiums. Concerns about extreme heat during the games taking place in the U.S., Canada, and Mexico have been mounting for months.

Worsening climate change, caused by burning oil, gas, and coal, is fueling dangerous heat across the globe. In the U.S., heat kills more people every year than all other weather-related events, including hurricanes, flooding, and tornadoes, according to the National Oceanic and Atmospheric Administration.

Preparations and Precautions

The National Weather Service issued an extreme heat watch for Philadelphia and surrounding regions starting Wednesday afternoon and into Saturday evening, with dangerously hot “feels-like” temperatures, another term for the heat index, up to 110 F during the daytime.

FIFA’s Fan Festival in Philadelphia is shifting its hours this week, including Saturday’s watch party, which will end at the conclusion of the 1 p.m. game. Spectators can check if they’re adequately hydrating by looking at the color of their urine — a light yellow is a good sign.

People on certain medications, older people, and those who aren’t heat-acclimated are among the most at risk. If somebody realizes that they’re hot, but they’re not sweating, or if they begin to feel a little bit dizzy, those are some signs that they really need to take a break, get inside, find some cooling, and drink plenty of water.

Original reporting: NBC Connecticut — read the source article.