Temperature
Keep your cigars at a consistent temperature of between 64 and 70 degrees Fahrenheit, or 18 and 21 degrees Celsius. Low temperatures will cause the cigar to age improperly and promote a bad, moldy flavor. Do not store your cigars in a cold area such as a cellar. Keeping your cigars at a high temperature can cause the cigar to rot and become the perfect breeding ground for worm infestations. Do not leave your humidor in an area where there is lots of heat from sunlight. Sunlight may affect the humidor itself, warping the wood.
Setting Up the Humidor
To achieve the correct temperature in your humidor, you must ensure that the relative humidity is between 65 and 75 percent. Set up the humidor by removing it from its package. Wet it by using distilled water or a mixture of 50 percent distilled water and 50 percent propylene glycol. Wipe off any excess water from the humidifier, and place it back in the humidor. Place a small shot glass or espresso glass full of distilled water in the humidor, and allow it to sit for 72 hours. Warm the distilled water to quicken the process. The humidor will begin to heat up, and the humidity will rise.
Hygrometer
Use a hygrometer to get the correct humidity-to-temperature ratio. Set up the humidor, and place the hygrometer inside the humidor. Once the hygrometer reads a steady 68 to 72 percent inside the humidor, you can place cigars inside. A hygrometer will have a 2 percent margin of error when reading the humidity-to-temperature ratio inside the humidor. If the hygrometer does not reach between 68 and 72 percent within 72 hours, or the reading fluctuates wildly from day to day, your hygrometer may need adjusting.
If the hygrometer is not reading correctly, you can calibrate it using the wet towel method. Wrap a towel that is damp around the hygrometer. Leave it wrapped for 10 minutes. The hygrometer should read 95 percent for the humidity-to-temperature ratio. If it does not, use a small screwdriver to adjust the hygrometer.