Afghanistan has an arid continental climate with considerable temperature and precipitation variation between seasons. Temperatures also vary greatly by altitude, with mountainous regions experiencing temperatures well below zero on an annual basis, yet southern arid regions regularly experiencing temperatures over 35ºC. Precipitation varies considerably with topography, with the southwestern arid region typically experiencing less than 150 millimeters (mm) of precipitation each year, and the northeastern mountain range experiencing more than 1,000 mm. Conditions in Afghanistan also have a complex intra-annual interaction with large-scale climate phenomena, specifically the El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole. The latter is associated with drought conditions in Afghanistan.