I think it also what you usually live in. Living up in the Canadian border, and heading to the gulf states in August won't be enjoyable. Yet, people living in those states do it all the time.
Also, humidity is a major factor when riding, especially when ATGATT. High humidity prevents the body from cooling itself with perspiration, thus higher internal body heat. This is what heat strokes are made of. Add the insulating factor of gear, and you can really run into danger. Living in C. Florida, mid 90's with relative humidity at 80-95%, I don't ride as much. Less trips, shorter trips, morning or evening time, and lots of water with stops into places w/ A/C. Riding in extreme temps (hot or cold), requires due diligence to stay safe.