An unprecedent early-season heat wave is occuring across the Southwest and southern California, with some of the earliest triple-digits readings likely setting new records.

An expanding upper-level ridge is developing across the West with high pressure producing abundant sun-filled days and warm nights.

Each day this week will become progressively hotter, with interior southern California, the lower Colorado River basin and southern Arizona, easily climbing into the triple digits Wednesday. This hot weather will last into the weekend.

Although these areas are no strangers to extreme heat, this heat wave is early. Phoenix doesn't see its first triple-digit day until early May and several locations across southern California could set new all-time monthly high temperature records later this week and this weekend as highs climb into the 105 to 110 degree range.

Remember, drink plenty of water to stay hydrated as the temperatures rise, but do not try to cool off in waterways, lakes and reservoirs yet. Water temperatures are still cold from the winter and hyperthermia could occur rapidly.