XTherm Shorty Q

I tested this once by laying on one in my house when the temperature was about 75F. It felt perfectly fine. There is no static sleeping pad that will be too warm at night. If it's so warm outside (say, 90F in summer in Phoenix) at night that you're too hot, it won't matter whether you're on a sleeping pad or R=0.1 pool float or on dirt – you're going to be hot. Now, if you like to lounge on a pad during the day to rest, then yeah it might be too hot. If though, at night, you're laying down and it's hot enough that you need to take off your quilt, then pad won't matter at that point, whether it's R1 or R10.

In reality, the insulation of the pad works both ways: technically it'll insulate from hot ground (keeping you relatively cooler) as well as obviously insulating you from cold ground (keeping you relatively warmer).

Practical answer: even in the coldest imaginable temperatures in the Sierras in June, they Xtherm will keep you comfortable, even on snow. In normal temperatures, say, 20F-60F just to cover a wide range, you'll be comfortable so long as your quilt is warm enough.