1. Before you plan a mobile office day, check the weather reports for humidity. Anything above 80 percent should make you cautious, although your device may have its own humidity specifications. Really humid weather can escalate that condensation effect we mentioned before, shorting out your circuits. But even if it doesn't do damage, excess moisture in and around your machine can trigger the built-in water damage sensor, sometimes voiding your warranty.
2. heat usually comes with lots of direct sunlight. We've heard all the urban legends about your laptop's screen becoming damaged from sun exposure, but we can't find anything to support it. Either way, it's better to be safe (and cool!) than sorry. But if you have to work in direct sun, make it easy on your eyes. Go for a dorky-looking laptop hood or attach an anti-glare screen cover.
3. Don't forget to turn off your laptop whenever you go outside or if you must leave your laptop in your car.
4. Don't walk and work with your laptop open. If you're moving from the cool A/C to sweltering heat, or from outside to indoors, shut your laptop down. Let it adjust to the new temperature before starting it up again. Condensation can build up inside your machine just like on your glasses.