Everyone hears about the "Heat Index" but many don't understand what it is. The Heat Index figures temperature and humidity to equal what the outside temperature feels like. A high heat index can cause illness and death to both humans and pets. Here are some problems which can occur. Heat Index between 80 - 90F = Fatigue possible with prolonged exposure and/or physical activity. Heat Index between 90 - 105F = Sunstroke, muscle cramps, and/or heat exhaustion possible with prolonged exposure and/or physical activity. Heat Index between 105 - 129F = Sunstroke, muscle cramps, and/or heat exhaustion likely. Heatstroke possible with prolonged exposure and/or physical activity. Heat Index of 130F or higher = Heat stroke or sunstroke likely. Pets like people need shade and plenty of water to limit the chance of heat related problems. Seek medical attention for anyone experiencing symptoms.