Weather Averages in Austin
Austin is located within the middle of a unique, narrow transitional zone between the dry deserts of the American Southwest and the lush, green, more humid regions of the American Southeast. Its climate, topography, and vegetation share characteristics of both. Officially, Austin has a humid subtropical climate under the Köppen climate classification. This climate is typified by very long and hot summers; short, mild winters; and pleasantly warm spring and fall seasons in-between. Austin averages 34.32 inches (872 mm) of annual rainfall and it is distributed mostly evenly throughout the year, though spring and fall are the wettest seasons. Sunshine is common during all seasons, with 2,650 hours, or 60.3% of the possible total, of bright sunshine per year.
Summers in Austin are very hot, with average July and August highs frequently reaching the high-90s (34–36 °C) or above. Highs reach 90 °F (32 °C) on 116 days per year, of which 18 days reach 100 °F (38 °C). The average daytime high is 70 °F (21 °C) or warmer every day between March 6 and November 20, rising to 80 °F (27 °C) or warmer between April 14 and October 24. The highest ever recorded temperature was 112 °F (44 °C) occurring on September 5, 2000, and August 28, 2011. An uncommon characteristic of Austin’s climate is its highly variable humidity, which fluctuates frequently depending on the shifting patterns of air flow and wind direction. It is common for a lengthy series of warm, dry, low-humidity days to be occasionally interrupted by very warm and humid days, and vice versa. Humidity rises with winds from the east or southeast, when the air drifts inland from the Gulf of Mexico, but decreases significantly with winds from the west or southwest, bringing air flowing from Chihuahuan Desert areas of West Texas or northern Mexico.
Winters in Austin are mild with cool nights, although occasional short-lived bursts of cold weather known as “Blue Northers” can occur. January is the coolest month with an average daytime high of 61 °F (16 °C). The overnight low reaches or exceeds freezing 19 times per year, and sinks below 45 °F (7 °C) during 88 evenings per year, including most nights between mid-December and mid-February. Lows in the upper 30s also occur commonly during the winter. Conversely, winter months are also capable of occasionally producing warm days. On average, eight days in January reach or exceed 70 °F (21 °C) and one day reaches 80 °F (27 °C). The lowest ever recorded temperature in the city was −2 °F (−19 °C) on January 31, 1949. Roughly every two years Austin experiences an ice storm that freezes roads over and cripples travel in the city for 24 to 48 hours. When Austin received 0.04 inches (1 mm) of ice on January 24, 2014, there were 278 vehicular collisions. Similarly, snowfall is rare in Austin. A snow event of 0.9 inches (2 cm) on February 4, 2011, caused more than 300 car crashes and a 13-inch (33 cm) snowstorm brought the city to a near standstill in 1985. The most recent major snow event occurred on December 7, 2017, when 1.3 inches was recorded at Austin-Bergstrom International Airport.
Typical of Central Texas, severe weather in Austin is a threat that can strike during any season. However, it is most common during the spring. According to most classifications, Austin lies within the extreme southern periphery of Tornado Alley, although many sources place Austin outside of Tornado Alley altogether. Consequently, tornadoes strike Austin less frequently than areas farther to the north. However, severe weather and/or supercell thunderstorms can occur multiple times per year, bringing damaging winds, lightning, heavy rain, and occasional flash flooding to the city. The deadliest storm to ever strike city limits was the twin tornadoes storm of May 4, 1922, while the deadliest tornado outbreak to ever strike the metro area was the Central Texas tornado outbreak of May 27, 1997.