# Extreme Heat *Environmental Hazard* When the temperature is 100 degrees Fahrenheit or higher, a creature exposed to the extreme heat and without access to drinkable water must succeed on a Constitution saving throw at the end of each hour or gain 1 [Exhaustion](Mechanics/CLI/rules/conditions.md#Exhaustion) level. The DC is 5 for the first hour and increases by 1 for each additional hour. Creatures wearing Medium or Heavy armor have [Disadvantage](Mechanics/CLI/rules/variant-rules/disadvantage-xphb.md) on the save. Creatures that have [Resistance](Mechanics/CLI/rules/variant-rules/resistance-xphb.md) or [Immunity](Mechanics/CLI/rules/variant-rules/immunity-xphb.md) to Fire damage automatically succeed on the save. *Source: Dungeon Master's Guide (2024) p. 68*