External heat and LED flashlights

I have read about the problems with LED flashlights and heat. I know that heat can be damaging to the LED if it is not well dissipated. I was wondering about the effect of external heat on LED flashlights. I regularly leave my flashlight in the car and here in Australia, the temperature can easily reach 45°C or 115°F. Inside the car, it must get even hotter than than that, possibly 60°C or 140°F.

Are these kind of temperatures likely to damage the LED within the flashlight? If so, what am I likely to notice with the flashlight?

45°C to 60°C won't damage the LED. It will get hotter during normal usage.
The bigger problem are the batteries, but normally li-ion should not be too much bothered by that. I had a Mag 4D flying around for around 2 years in my car with alkalines and hat no problems with it, now i have 2 lights with cr123s in the car and they both work flawlessly.

It might become a problem, if you turn on the flashlight at 60°C. But as long as it's switched off, the LED won't mind. It gets way hotter in use. And who needs a flashlight, when the sun is burning down like this?

I would say that any damage is unlikely if the flashlight is switched off at the time. It's the actual junction temperature of the LED which causes damage.

When your light starts to feel warm to the touch in use, the junction of the diode will be considerably hotter as there will always be some amount of thermal resistance between it and the casing of the light. After all, the heat has to conduct through the die itself, the emitter body, the pill that the emitter is bonded to, the joint between pill and casing and the casing itself, before the person holding it can feel the heat. Based on all this, my (entirely unscientific and unproven) guess is that the junction may be 30 or 40 degrees C hotter than the casing of the light when running at it's rated power level (may be more, may be less, somebody else may have researched this? Also, what sort of junction temperature would you have to reach to permanantly damage an LED?)

Of course, if the light has been subject to the temperatures that you stated, and you then run it at full power in an ambient temperature of 60 degrees C, then you may have difficulty.

Trying to remember some basic thermodynamic stuff from my school days...

Rate of thermal energy transfer is proportional to (1)the difference in temperature (think that was one of Newton's Laws of Thermodynamics if I remember right?) and (2) the thermal resistance.
Thermal resistance is a constant, determined in this case by the construction and materials of your flashlight, and the rate of energy transfer is the thermal power output of your LED, which for a given power output is also a constant; this leaves the temperature difference as the only variable. Which means that unless the ambient temperature drops, the LED junction temperature must increase for a given power output!

If you avoid running at high power levels while the ambient temperature is extremely high then you shouldn't encounter any problems