Not all of the Round of 32 matches in the World Cup will be affected by the heatwave but there will be some notable games to keep an eye on.
The hottest weather this week will be in Texas which will mostly impact fans travelling to and from the air-conditioned stadiums in Houston and Arlington.
In Houston for Brazil v Japan on Monday the 'feels like' temperature will be around 44C (111F) and in Dallas on Tuesday up to 41C (106F).
It will obviously feel much more pleasant inside the stadiums for players and fans.
This is also likely to be the case for England v DR Congo on Wednesday in Atlanta where it will also feel hot and humid outside of the air-conditioned stadium.
Elsewhere, some of the matches where the heat could be an issue;
Tuesday 30 June - France v Sweden, New Jersey - 30C (86F).
Thursday 1 July - Portugal v Croatia, Toronto - 31C (88F).
Friday 2 July - Argentina v Cape Verde, Miami - 31C (88F).
Friday 2 July - Colombia v Ghana, Kansas City - 32C (90F).
The games on Friday in Miami and Kansas City could be especially uncomfortable as the high humidity here will push the feel like temperature up to 40C (104F).
In the official measure of how heat and humidity affects the human body - known as 'Wet Bulb Global Temperature' - both these matches may have an index close to the threshold where Fifapro consider it 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 we head into the last 16 round in Philadelphia and New Jersey on Saturday and Sunday where temperatures will be way above normal.
Temperatures will soar into the high 30'sC (100F) where it will feel like over 40C (104F).