Dell :: 1330 Overheats In Hot Weather Only

My 1330 laptop (with 8400m graphics) seems to overheat and become unstable when the ambient temperature is high. In the Bay Area where I live it is generally fine, but on a couple of recent summer trips to Phoenix and Vegas the hot weather made it unstable;

it would often run very slowly or just crash continuously. I've also seen this instability during a recent spate of hot weather here in the Bay Area, and it also happens when I try videoconferencing with skype even in mild weather here. I assume the videoconferencing just stresses the hardware more than anything else I do (I am not a gamer).

It seems clear to me that this is a heat issue, but because it usually manifests while travelling not at home, a fan pad doesn't seem like an appropriate solution