FORECAST: Earliest 100-degree day recorded, with more to come

A strong ridge of high pressure is building over the Desert Southwest, sending temperatures nearly 30 degrees above normal by the end of the week.

Triple-digit heat isn't going away this week!

By: Justin Hobbs

PHOENIX — Wednesday marked not only the earliest 100-degree day for Phoenix but the hottest day in March ever. However, the month is not over yet, and we are likely to hit higher temperatures by the end of the week.

A strong ridge of high pressure is building over the Desert Southwest, sending temperatures nearly 30 degrees above normal by the end of the week.

As we head into Thursday, we’re forecasting the earliest 105° day on record, more than a month earlier than the previous earliest, which was April 20, 1989. The temperatures will keep climbing into Friday and Saturday.

The dangerous early-season heat has prompted the National Weather Service to issue an Extreme Heat Warning for the Valley Thursday through Sunday. Parts of Yavapai and Mohave counties and the Grand Canyon below 4,000 feet are under that warning through Sunday.

Thursday through Sunday are also ABC15 Weather Action Days. Take precautions.

If you plan to be outdoors, limit strenuous activity during the hottest part of the day and drink plenty of water.

Some trails will be closed to protect hikers, including parts of South Mountain, Piestewa Peak, and Camelback Mountain. First responders and dogs are not permitted on trails when temperatures reach 100 degrees or higher.

Highs could push toward 105 degrees Thursday through Saturday. Phoenix typically does not see heat like that until late May.

Several records could fall this week in the Valley, including the earliest 100-degree day, the earliest 105-degree day, the hottest March temperature ever recorded, and the most triple-digit days in a single March.

The peak of the heat dome arrives Friday into Saturday. Temperatures ease back into the low 100s next week, but that is still well above normal for late March.