How is it expected to affect us?

The growing consensus of heatwave 3 seems to be a standard affair with the block never establishing itself over europe and retreating west to allow a northerly flow later.  

Since the models had been showing often those low 40's becoming more frequent showing it likely sooner than later to happen at some point so not to ignore.  Very dry run on the ensembles and with uppers going to 15C as more members clustering together plus with very dry ground might get to low 30's here.  Last rain that give a dusting dampness last week Monday storm that missed here.

I've posted a static chart and animation of it here:

https://www.theweatheroutlook.com/signal#rep609 

One testament to how hot it is is that in that ensemble we are actually seeing some diurnal variation in the T850s, with it dropping by 5C at night compared to the day. When the airmass temperature becomes extreme you start to get mixing and this dirunal variation starts to appear; its not usually seen in the UK (other than sometimes in Spring when you get a very cold airmass).

Its also why despite global warming causing ever more extreme temps in higher latitude the all time global temp record is probably not going to fall anytime soon. When you get much above 50C the heat spreads out to an increasingly deep column of air and stops further surface heating. 

Another reason is that the global all-time max temperature record is almost certainly an incorrect reading. But I digress...

 Yes I agree, it should be removed in favour of the 2013 death valley record of 54.0C, similar temperatures were also recorded in Kuwait which is also a realistic place for them to happen. The Lut desert in Iran doesn't have any weather stations but holds the record for the highest surface temperature, so this is also a possible candidate if we can get stations there. 

The other small point is that these are 'non heat burst' related records. Heat bursts can cause temperatures to easily exceed 60C in the most extreme examples. Its only a matter of time before a heatburst happens in the locality of a station and then we will have to work out what to do.