1: 1. Dehydration risk increases with caffeine consumption in hot weather.

2: 2. Caffeine can elevate core body temperature, leading to heat-related illnesses.

3: 3. Increased heart rate from caffeine can stress the body in extreme heat.

4: 4. Caffeine diuretic effects combined with heat can lead to faster dehydration.

5: 5. Avoiding caffeine can help regulate body temperature in hot summer weather.