Much of the country has already experienced its first 90-degree day, and summer is just warming up. While the sun may be brutal outside, inside your cab, it can get downright dangerous. Consider:

On an 80-degree day, your cab's interior can reach 99 degrees in just 10 minutes and 114 degrees in 30 minutes.

On a 90-degree day, your cab's interior can reach 109 degrees in just 10 minutes and 124 degrees in 30 minutes. (Source: Noheatstroke.org).

Simply put: The hotter it gets outside, the warmer it gets inside your cab. If you don't find a way to stay cool, you could develop one of three heat-related health conditions:

Heat Cramps: Typically the first signs of a heat-related illness, heat cramps are painful, involuntary muscle spasms most often caused when your body loses water and electrolytes through sweating. They usually occur during heavy exercise in hot environments. The spasms may be more intense and last longer than typical nighttime leg cramps.

Heat exhaustion: This second form of heat illness happens when your body loses larger amounts of water through sweating. Signs can include heavy sweating, clammy skin, a fast and weak heartrate, nausea or vomiting, muscle cramps, fatigue, dizziness, headache or passing out.

Heat stroke: This is the most serious form of heat illness and can cause brain damage if left unchecked. It happens when your body can no longer control its temperature. Symptoms include a fever of 103 degrees or higher, an inability to sweat, dry and red skin, a racing pulse, dizziness, nausea, confusion and passing out.

Reduce your risk for heat-related illness. Follow these 5 tips:

1. Hydrate regularly. Drink water or a sports drink with electrolytes. Avoid coffee, soda or other drinks with caffeine, which may dehydrate you. Know your body and increase your fluid intake as your activity levels increase.

2. Look for cool places to rest and stop. Anti-idling laws in some states prevent you from sleeping with the air-conditioning (A/C) on. Seek shaded spots or park at a rest stop that has A/C so you can head inside to cool off.

3. Wrap a cool, wet towel around your neck to cool down. Put it back in your rig's fridge when you aren't using it to keep it cold.

4. Wear loose-fitting, light-colored, lightweight clothing so your skin can sweat and your body can remove excess moisture.

5. Wear sunscreen. Apply it regularly to avoid “trucker's arm" — a sunburn on your left arm, where it rests by the window. Any case of sunburn can make it harder for your body to regulate its own temperature.

If you notice the signs of heat stroke or exhaustion, stop what you're doing immediately, loosen all clothing and get to a cool, shaded area — fast. If your body temperature reaches 104, call 911.