Phoenix Shatters March Heat Records with Earliest 100-Degree Day
Phoenix is experiencing an unprecedented heat wave that has rewritten the record books for March. In a historic weather event, the Valley reached triple-digit temperatures far earlier than ever before, signaling a dangerous start to the spring season.
Historic Triple-Digit Heat in March
On Wednesday, March 18, 2026, Phoenix Sky Harbor Airport reached 100 degrees at 2:57 p.m., marking the earliest occurrence of 100° in Phoenix history. This shattered the previous record set on March 26, 1988. The heat intensified throughout the afternoon, hitting 102 degrees by 5 p.m., which established a new record for the warmest day ever recorded in March [AZFamily].
This temperature surge blew past the previous daily high record of 95 degrees set in 2017. According to data from Extreme Weather Watch, the record high for March 18 was pushed to 102 degrees in 2026.
Extended Forecast and Extreme Heat Warnings
The heat is not a brief spike but part of a strong ridge of high pressure dominating the region. Forecasters expect temperatures to remain more than 20 degrees above average through the beginning of the following week. Key projections include:
- Friday Peak: Temperatures are expected to hit 107 degrees, which would be the earliest 105+ temperature ever recorded and the hottest temperature ever recorded for the entire state of Arizona in March.
- Weekend Outlook: Highs are projected to reach near 106 degrees on Saturday and 101 degrees on Sunday.
Due to these dangerous conditions, an Extreme Heat Warning was issued for the Valley, most of South-Central Arizona and Western Arizona (including communities below 4,000 feet in Northern Arizona) [AZFamily].
Key Takeaways: March 2026 Heat Event
- Earliest 100° Day: March 18, 2026 (Previous: March 26, 1988).
- New March Record: 102°F reached on March 18.
- Statewide Impact: The projected 107°F on Friday would beat the all-time March record for the state of Arizona.
- Timing: This extreme heat is occurring over two months earlier than average.
Understanding the Context of Arizona Heat
Although this March event is historic, it is helpful to compare it to Arizona’s all-time extremes. The hottest temperature ever recorded in the state remains 128°F, set on June 29, 1994 [Weather On This Day]. However, the arrival of 100-degree weather in mid-March is an anomaly that deviates significantly from typical seasonal patterns.
Frequently Asked Questions
How does this compare to previous years?
This is the earliest 100-degree day ever recorded in Phoenix, beating the 1988 record by eight days.
What caused this sudden spike?
A strong ridge of high pressure is currently dominating the weather pattern over the Valley, pushing temperatures well above seasonal averages.
Is this the hottest March on record?
Yes, as of March 18, 2026, the Valley recorded its warmest day in March ever, reaching 102 degrees.