Pure water boils at a temperature of 100 degrees Celsius, or 211.9 degrees Fahrenheit. This standard assumes an external atmospheric pressure of 1 bar or the standard pressure at sea level. According to About.com, changes in air pressure can raise or lower the boiling point of water.
Many factors influence the temperature at which water boils. Lower pressure lowers the water's vapor point and allows it to boil at lower temperatures. The presence of dissolved solutes in the water also affects the boiling point, according to About.com. Water with salt dissolved in it, for example, boils at higher temperatures than distilled water.