phoenix AZ weather

Phoenix, Arizona, is renowned for its hot desert climate, characterized by long, scorching summers and short, mild winters. This climatic pattern is typical of the Sonoran Desert, making Phoenix the largest city in the Americas within this climatic zone. The city experiences approximately 300 days of sunshine annually, accounting for over 85% of daylight hours, positioning it among the sunniest regions globally.

Temperature Extremes

Phoenix’s summers are notably intense, with average high temperatures ranking among the hottest of any major U.S. city. On average, there are 111 days each year with highs reaching at least 100°F (38°C), predominantly from late May through late September. Temperatures exceeding 110°F (43°C) occur on average 21 days annually. The record high temperature stands at 122°F (50°C), recorded on June 26, 1990.

In recent years, Phoenix has experienced unprecedented heatwaves. In July 2023, the city recorded an average daily mean temperature of 102.7°F (39.3°C), marking the first instance of a major U.S. city averaging over 100°F for a month. This period also included a 31-day streak of temperatures exceeding 110°F. The following year, 2024, saw even more extreme conditions, with a record 70 days of temperatures surpassing 110°F and a 113-day streak of highs over 100°F, lasting from May 27 to September 16.

Precipitation Patterns

Phoenix receives minimal rainfall, with an average annual total of 7.22 inches (183 mm) at Phoenix Sky Harbor International Airport. The city’s dry and sunny weather is occasionally interrupted by Pacific storms during winter and the North American monsoon in summer. The monsoon season, officially spanning from June 15 to September 30, elevates humidity levels and can result in heavy localized precipitation, flash floods, hail, destructive winds, and dust storms known as haboobs.

Recent Weather Events

In early March 2025, Phoenix experienced a series of weather disturbances leading to increased cloud cover, cooler temperatures, and precipitation. On March 5, 2025, forecasts predicted a 60% chance of showers, with daytime highs near 58°F (14°C) and nighttime lows in the lower 40s°F (5-7°C). These conditions marked a significant departure from the typically dry and warm weather associated with the region.

Air Quality Concerns

Phoenix faces challenges related to air quality, particularly concerning ozone pollution and particulate matter. In 2024, Maricopa County, encompassing Phoenix, was ranked seventh in the United States for ozone pollution by the American Lung Association. Vehicle emissions are significant contributors to ozone formation. Additionally, the city contends with high levels of particulate pollution, including PM2.5 from diesel exhaust and larger PM10 particles from dust. Exposure to elevated concentrations of PM10, especially during dust storms or disturbances at agricultural or construction sites, poses health risks such as Valley Fever, a fungal lung infection.

Urban Heat Island Effect

Unlike many desert locations that experience significant temperature fluctuations between day and night, Phoenix’s urban heat island effect moderates this variation. As the city has expanded, average summer low temperatures have risen steadily. Infrastructure such as pavement and buildings absorb and retain heat, radiating it during nighttime. Consequently, the daily normal low temperature remains at or above 80°F (27°C) for an average of 74 days each summer. On July 19, 2023, amid an intense heatwave, Phoenix recorded its highest daily low temperature at 97°F (36°C).

Seasonal Climate Overview

Spring: Characterized by blooming cacti and wildflowers, spring in Phoenix offers daytime temperatures averaging around 80°F (27°C), with comfortably cool evenings.
Summer: Extremely hot, with prolonged periods of temperatures exceeding 100°F (38°C). The monsoon season introduces increased humidity and potential for severe weather events.
Autumn: Gradual cooling occurs, with temperatures transitioning from the summer highs to more moderate levels. This season is typically dry and sunny.
Winter: Mild temperatures prevail, with average highs ranging from the mid-60s to low 70s°F (18-23°C). Precipitation is infrequent but can occur due to Pacific storms.

Climate Change Implications

The rapid warming trend in Phoenix aligns with broader global patterns driven by human-induced greenhouse gas emissions. Warmer springs can lead to early snowmelt, jeopardizing summer water supplies and increasing wildfire risks. The Southwest and West regions are experiencing the fastest warming, particularly in fall.

Dust Storm Hazards

Dust storms, or haboobs, are significant weather phenomena in Phoenix, especially during the monsoon season. These storms can severely reduce visibility and pose health risks due to airborne particulate matter. For instance, on March 1, 2025, a multi-vehicle collision near Phoenix, amid blowing dust and poor visibility, resulted in four fatalities. The accident occurred during dust storm advisories issued by the National Weather Service, with wind gusts up to 40 mph contributing to reduced visibility.