Keep calm and carry one of these.
Stone of Coldness
A stone of coldness, if kept on one's person such as in a pocket or a pouch, will keep one comfortably cool even in the most sweltering heat and humidity. If held in one's hand, it will extend the zone of protective coolness in a 4 cubit* radius. If held in both hands and rubbed, it will reduce the temperature enough to freeze water rapidly at a distance of 8 cubits.** This third function will cause 1d8 hit points of damage to creatures that are especially vulnerable to low temperatures. A successful saving throw vs. magic will reduce the damage to one half.
Like other magic stones, a stone of coldness has no standard size, shape, or coloration, and will only activate when in close proximity to a living creature.
* 6 feet or 2 m.
** 12 feet or 4 m.