PHOENIX (AP) — The first day of summer is forecast to bring some of the worst heat the southwestern U.S. has seen in years.

The forecast calls for 119 degrees in Phoenix, where some flights have been canceled because certain planes can’t take off in extreme heat.

Arizona is seeing the most stifling temperatures, but the wrath of the heat wave is being felt across Nevada and California as well.

Las Vegas was forecast to hit 117 on Tuesday and excessive heat warnings cover almost all of California.

Phoenix hit 118 degrees on Monday, which the National Weather Service says is quite rare. In fact, temperatures of 118 or above have only been recorded 15 times since records were first kept in 1896.

Forecasters also warned Phoenix could hit 120 degrees this week.

Phoenix has hit the 120 mark only three times in recorded history — the last time 22 years ago. The record high was 122 degrees, recorded June 26, 1990.

In addition to grounding flights of smaller planes, airlines have been taking other measures on larger jets to reduce their weight because of the heat.

American Airlines spokesman Ross Feinstein said the carrier began limiting sales on some flights to prevent the planes from exceeding maximum weight for safe takeoff in the hot conditions. Airlines can use other strategies for dealing with limitations on the planes during hot weather, including reducing the amount of luggage and cargo and not fueling completely to make the plane lighter for takeoff.