Heatwave may make World Cup matches unsafe this week

A large heatwave is expected to intensify across the central and eastern United States and much of Canada this week, raising concerns about player safety during World Cup matches. The National Weather Service (NWS) warned that temperatures will rise significantly, accompanied by high humidity, creating potentially dangerous conditions.

Heat indexes may approach the threshold where global players' union Fifpro considers it too unsafe for play, meaning some last-32 matches could face the hottest and most difficult conditions of the tournament so far.

Extreme temperatures forecast

Temperatures in excess of 32°C (90°F) are widely expected across the affected regions. With humidity, it will feel like temperatures up to 46°C (115°F) across portions of the Southern Great Plains, mid-Mississippi Valley, and eventually parts of the mid-Atlantic, according to the NWS. Overnight temperatures may not fall below 20°C (70°F), classified as a "tropical night" by meteorologists.

The extreme heat will also affect eastern Canada, with temperatures forecast to be up to 10°C (18°F) above average in Ontario and Quebec.

Matches at risk

Not all Round of 32 matches will be affected, but several notable games are under scrutiny. The hottest weather will be in Texas, impacting fans traveling to and from air-conditioned stadiums in Houston and Arlington.

• Monday: Brazil vs Japan in Houston – 'feels like' temperature around 44°C (111°F).
• Tuesday: Dallas – up to 41°C (106°F).
• Wednesday: England vs DR Congo in Atlanta – hot and humid outside the air-conditioned stadium.

Other matches where heat could be an issue:

• Tuesday 30 June: France vs Sweden, New Jersey – 30°C (86°F).
• Thursday 2 July (overnight for UK viewers): Portugal vs Croatia, Toronto – 31°C (88°F).
• Friday 3 July: Argentina vs Cape Verde, Miami – 31°C (88°F); Colombia vs Ghana, Kansas City – 32°C (90°F).

The games on Friday in Miami and Kansas City could be especially uncomfortable, as high humidity will push the 'feels like' temperature up to 40°C (104°F). In the official measure of how heat and humidity affects the human body – known as Wet Bulb Global Temperature – both matches may have an index close to the threshold that Fifpro considers too unsafe to play.

By this weekend, the heat will peak across eastern areas of the US and Canada. This could be a particular issue as the tournament enters the last 16 in Philadelphia and New Jersey on Saturday and Sunday, where temperatures will be far above normal, soaring into the high 30s Celsius (100°F) and feeling like above 40°C (104°F).

Thunderstorms also a threat

High temperatures and humidity also raise the likelihood of thunderstorms. Initially, most wet weather and storms will be over the Northern Plains and Upper Midwest, away from World Cup host cities. Later in the week, thunderstorms may develop in the heatwave area, potentially affecting matches.

Thunderstorms only have to be within an eight-mile (13 km) radius of a stadium for a match to be suspended so that players and spectators can seek shelter. For England's game against DR Congo in Atlanta on Wednesday, there is currently a small risk of a thunderstorm that may affect the match, with a higher risk later in the afternoon after the game finishes. There is also a high chance of a thunderstorm affecting the Argentina vs Cape Verde last-32 game in Miami on Friday.