A bolt from the blue: lightning strike to the head.

We report an extraordinary event of a lightning strike to the head of a helmeted bicyclist that occurred under fair weather conditions with a cloudless sky. The patient sustained a cardiac arrest and hypoxic encephalopathy with residual neurologic impairment. With the availability of highly developed meteorologic equipment, we were able to determine that the lightning "bolt from the blue" probably originated in a thunderstorm that was about 16 km away and obscured by the mountains.