The US National Weather Service has issued heat advisories and extreme heat warnings for parts of California and Arizona as a ridge of high pressure drives temperatures significantly above seasonal averages this week.

Extreme heat warnings are in effect Monday and Tuesday for areas including Palm Springs, California, where temperatures could reach 40-43C (104-110F). Daytime highs are forecast to climb 10-15C above average across western parts of the United States and Mexico.

More broadly across the region, temperatures are expected to reach the high 30s celsius before the heat pattern shifts eastward toward the midwest later this week. The heat advisories cover multiple areas in California and Arizona as the high pressure system intensifies conditions.

The extreme temperatures are part of a broader weather pattern affecting the western United States and Mexico, with meteorologists tracking the movement of the high pressure ridge responsible for the unseasonable heat.

Meanwhile, other parts of the world are experiencing contrasting severe weather conditions, including deadly flooding in South Africa's Western and Northern Cape provinces, where heavy rains continue to impact the region.