In cold weather, canister stoves experience a drop in performance due to the lower vapor pressure and burner output resulting from the colder fuel. The temperature of the gas inside the canister governs the output pressure, which drops as temperature drops. This can lead to longer boil times and difficulty lighting the burner with the built-in piezoelectric ignitor. However, Jetpower's lower firing rate can reduce canister cooling and increase performance, particularly when using propane.
To ensure optimal performance in temperatures below freezing, it's recommended to keep the canister warm between uses by storing it in a warm pocket or sleeping bag and removing it immediately prior to heating your food. Insulating the canister by not placing it on a cold surface can also help. Despite the pressure drop, Jetboil stoves have been used by mountaineers up to 8,000 m (26,000 ft.) on Mt. Everest with great success. By keeping the canister warm before use, it's possible to use the stove with reasonable performance even in sub-zero temperatures.
Placing the canister on or in a small piece of foam to keep it insulated from snow can also help. Altitude itself isn't a significant problem as the pressure difference between the canister and the environment is greater for any given temperature, resulting in a higher effective gas flow rate even when the canister is cold. Additionally, the reduced oxygen causes the burner to burn richer, which can also be helpful in the cold. It's recommended to always carry an extra canister and keep it warm to swap out with a cold one when necessary, as well as carrying matches or a lighter as a backup.
For temperatures below 45 degrees Fahrenheit, Jetboil's MiniMo, Sumo, and Joule cooking systems are recommended, as they feature advanced Jetboil Regulator Technology to deliver consistent heat output down to 20° F (-6° C).