Its been a while since i have been into flying RC planes. i generally fly on weekends when i manage to get up by 12 pm. 
Because of this I have always manage to reach the field only by 2 pm or so...
Flying in scorching sun is uncomfortable because of the heat, but who cares we all love to fly! 
However the heat, I discovered is not good for the receiver and the plane.
I am using a RCB 7x radio system, which is a fairly good transmitter and never gave any range issues within recommended limits, until i started flying in the afternoons.
I repeatedly kept loosing control of the plane and it would fall off from the sky until suddenly from no where it would read signals from my tx and level again.
It broke 2 props and shook a bit of my confidence causing me to believe that I cannot land my planes safely anymore(felt Helis are so easy,my Hirobo sceadu 50 never troubles me  ).

But then this happened...

Today Pune has elections and I am not going to office so that i can help build a better nation. .
But to start of with the day I did go to the field at 6.45 am today(the maid woke me up ).
And yes, This time the plane flew like a charm. No lost signal, even when i pushed it to its absolute boundaries.
I was so happy to fly, it was a bliss. All my landings were perfect!!(conditions apply *)

I can say from this that the crashes that i had in the afternoons have definitely got something to do with the heat.
Maybe the overheated ESC caused the rx to loose signal

I cannot say for sure what may have caused this in specific but i am pretty damn sure that the heat played its role here.

Are there any ways that you folks use to overcome this??

P.S.: I observed this while flying my RCB blazer.

That's not due to the heat definitely
Many of us had that issues . I think it's the placement of the 2 antenna . Need to be kept far away from each other.
Wait  for the RcBazaar team to respond .

Worth reading.
http://www.rcindia.org/radios-and-receivers/crash-on-futaba-fasst/msg3296/#msg3296

Were your control surfaces working when you lost power to your plane? If they were working that would mean your Bec & Rx were working fine, probably power to motor was cutoff.

Me too been facing the same issue but on a Flysky 9ch tx and on a quad while flying in 40C. Quad goes into a freefall suddenly for a second then regains power. Motor and esc are warming up a lot more than they used to in winter but its still not hot.

Since in my case Rx is powered by FC which inturn is powered by 2 becs, only failure of both becs would kill the Rx but that would have also reset the FC so think bec's are working fine. Definitely problem with esc's powering motor but got to check some more things before arriving on any conclusion.

Many of have lots of issues with the rcb7x.

I personally don't think so that heat or flying in afternoon in sun causes any problem. I'd myself flew many times in afternoon but didn't faced any issues such as lossy transmissions or loosing control over plane as in your case.
The only thing that affects is sometimes in sun it gets difficult to see model or locate it when in air due to sun rays. Atleast I didn't faced any such problem. I use a flysky Tx and Rx.
You should contact RCB and consult them for this.