I don't think you can pin any nationality or race down to being better able to cope with high (or low) extremes of temperature. Me for example, originally from NZ of Welsh, Irish and English ancestry, came to Western Aus' as a 20 year old and got a job on a farm out in the Eastern wheatbelt. It got a little bit chilly during winter but I wasn't working in snow, ice, sheeting rain and rarely even a frost as I had been on a farm in Canterbury, NZ. I became aware that I was putting on dry boots every morning and my tootsys weren't cold all day.
In 1971 I took a job on railway construction in the Pilbara region over 1500 Km North of Perth and hot in summer, man I loved it. Inland hot, dry, on the coast hot, humid but winters are beautiful. I lived and worked there for 35 years. During that time I worked with people from all over the world some were poms who, like me, thrived in the heat and others couldn't tolerate it and left.
The son of friends who was born and raised, did his apprenticeship in the Pilbara went to Canada, fell in love with the place and now works at a ski resort as a snowboarding instructor. Says he loves the cold.
Most accommodation was air conditioned so you could sleep at night, the first air conditioned machine I operated, a front end loader, would have been in the mid 90's and didn't drive a truck with A/C until 2002.
The thought of going back to working, day in day out, in the snow or driving rain as I did in my youth, is not a pleasant one.
Cheers,
Geoff.