Heat is the Enemy of your guitar.
In general, your guitar is safe and comfortable at the same temperatures that you are safe and comfortable. A guitar can withstand heat up to about 110-degrees (F). Above that temperature, the glue that holds the instrument together begins to soften. In fact, luthiers who repair guitars use "heat guns" to heat glue joints and remove wooden parts for repair. Few realize the pressure that the strings exert on a guitar. If your Voyage-Air Guitar is folded open to the playing position, the strings will exert a combined pull of more than 100 pounds on the bridge of the guitar - exactly the same as hanging a 100-pound weight from the bridge! Now, imagine that 100-pound weight pulling on the bridge as its glue gets hot and begins to soften. The bridge can easily lift, or even pull from the top of the guitar. Heat is the enemy. Protect your guitar from heat.
When subjected to heat, the wood of your guitar suffers. The natural moisture-content is baked out of the wood, and the wood begins to shrink. Usually, the first sign that a guitar has been subjected to heat is the ends of the frets begin to protrude from the fretboard. Other signs are bulges and warps in the top of the guitar, or binding that has become loose or actually popped away from the edges of the tops and sides.
If your guitar must travel with you where it's warm (or downright hot), keep the guitar in its Voyage-Air Guitar carry case. All Voyage-Air Guitar cases have padded insulation that helps protect the instrument from heat.
Never keep your guitar locked in your car on a hot day.
The interior of a closed car can easily reach 170-degrees! On a hot day, never leave your guitar in the direct sun, even in its case.