Why the Hottest Time of Year Varies Widely Across the USA

When is the hottest time of year, in the United States? Although the entire country sits within the Northern Hemisphere and thus experiences the same summer solstice, the hottest time of year doesn’t arrive all at once across the country. In this video we explore three different sections of the contiguous United States, where the hottest time of year comes as early as June and as late as September. These differences are key to understanding the climate of the USA. Special attention is directed toward the Southwest Monsoon region (Arizona, New Mexico, West Texas), and part of the South-Central United States (Texas, Oklahoma, Arkansas, Louisiana.)


Image Sources:

Daniel Davis (self)
Google Earth/Maps
NASA Earth Observatory
earth.nullschool.net
texashistory.unt.edu
Oklahoma Historical Society
Wikipedia Commons: Scott Ellis, Debivort.

Information Sources:

NOAA

Influence of the North American Monsoon System on the U.S. Summer Precipitation Regime. Journal of Climate, 1997. Higgins, Yao, Wang.

Multiscale Variability of the Flow during the North American Monsoon Experiment. Journal of Climate, 2007. Department of Atmospheric Science, Colorado State University. Johnson, Ciesielski, McNoldy, Rogers, Taft.

Understanding the Dominant Sources and Tracks of Moisture for Summer Rainfall in the Southwest United States. Journal of Geophysical Research, 2018. Jana, Ray, Rajagopalan, Alexander.

Southwestern United States Summer Monsoon Source—Gulf of Mexico or Pacific Ocean?
John E. Hales, Jr. Journal of Applied Meteorology (1962-1982)

Seasonality of coastal upwelling off central and northern California: New insights, including temporal and spatial variability. M. García-Reyes, J. L. Largier. Journal of Geophysical Research, 17 March 2012.

Elford, C.R., 1970, The Climate of California, in National Oceanic and Atmospheric Administration, U.S. Department of Commerce, Climate of the United States, v. 2, p. 538-546.

The Diablo Winds of Northern California: Climatology and Numerical Simulations. Bowers, Carrie. San Jose State University, 2018.

River Navigation in the South-Central USA:
Grant Foreman (1928). River Navigation in the Early Southwest. The Mississippi Valley Historical Review, 15(1), 34–55. doi:10.2307/1891666 

Instream Flow Study of the Middle and Lower Brazos River. Texas Instream Flow Program, Brazos River Authority. March 2010.

Ecoregion of North America. US EPA.

Carey, Jennifer H. 1992. Quercus marilandica. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.

Shortleaf pine-bluestem restoration in the Ouachita National Forest. USDA Forest Service, 2007. Larry D. HedrickGeorge A. BukenhoferWarren G. MontagueWilliam F. Pell. James M. Guldin.