Dallas, situated in North Texas along the Trinity River, features a humid subtropical climate (Köppen Cfa) defined by mild winters and hot, humid summers. Summers are intense, with average July and August highs near 96°F and an all-time recorded maximum of 113°F set during the severe heat wave of 1980. Spring and autumn bring warm, pleasant weather and vibrant wildflowers, though spring is highly volatile as cold fronts from Canada collide with Gulf moisture, generating severe thunderstorms, hail, and occasional tornadoes. Winters are generally mild (January averages a high of 57.7°F), but sudden "Blue Norther" cold snaps can trigger freezing rain and dramatic temperature drops—including the all-time low of -3°F recorded on January 18, 1930. Snowfall is rare (averaging just 2.6 inches annually, with a record 12.5 inches falling in February 2010), yet as the city lies at the lower end of Tornado Alley, destructive events have struck, including an F3 tornado in 1957 and a deadly Fort Worth tornado in 2000.