Summer heat shortens battery life dramatically. In desert and southern markets, batteries that would last five years in cooler climates often need replacement at three.
Pavement temperatures above 140°F in mid-summer cause tire blowouts at highway speeds — usually older tires with developing sidewall weakness.
AC compressor seizures spike during the first multi-day heat wave each summer. The compressor that was 'fine' all winter fails at the first hard demand.
Fuel pump failures cluster in summer. Running the tank low in hot weather overheats the fuel pump (which is cooled by surrounding fuel).
Engine overheating becomes a real risk. Cooling system components that were marginal in winter may fail under summer load. Check coolant level monthly.