Don't let your guard down just yet if you live in the Southwest. Triple-digit heat is returning this week after the first week of September was only in the 90s.

Although the Desert Southwest and southern Great Basin have had an extremely hot summer, triple-digit highs in September aren't unusual. The recent roller coaster will force everyone to get reacclimated to the extreme heat once again this week. Extreme 105- to 110-degree highs expand into interior Southern California and the Great Basin through the end of the week.

The TemperatureRadar is a great tool to use to track this week's extreme heat. Las Vegas and Arizona visitors and residents should follow heat safety guidelines, including staying hydrated with non-caffeinated and non-alcoholic beverages and limiting outdoor activities during the afternoon.