Remarkably hot weather in southern Texas results when Mexican Plateau air is advected eastward over south Texas and mixed down to the surface. Laredo reached 103F on February 20,1986 in this type of setting. The mixing of the Mexican Plateau air to the surface over south Texas occurs most often under the northeast edge of a 500mb high.

Similar synoptic settings have produced unusually hot single day episodes of heat during the spring and summer months as far north as North Dakota and New England.