How hot is lava?

Measuring the temperature of lava. Photograph by R.L. Christiansen, U.S. Geological Survey, January 9, 1973.

The temperatures of lavas vary depending on their chemical composition. Hawaiian lava (basalt) is usually around 1100 C. Volcanoes such as Mt. St. Helens erupt lava that are around 800 C.

Here is a list of temperatures for the common types of lava:

Rock type	Temperature (C)	Temperature (F)
Rhyolite	700-900	1292-1652
Dacite	800-1100	1472-2012
Andesite	950-1200	1742-2192
Basalt	1000-1250	1832-2282

See question 3 in this section for the chemical compositions of these lavas.

Source of information:
Francis, P., 1993, Volcanoes: a planetary perspective: Clarendon Press, 443 p.