MENU

NOAA National Centers
for Environmental Information

State Climate Summaries

TENNESSEE

Key Messages   Narrative   Downloads  

Up and Over the Mighty Mississippi, Plate 2
Photo by Thomas Hawk

TENNESSEE

Tennessee’s central location in the southeast, some distance from ocean bodies of water, exposes it to both warm and humid air from the Gulf of Mexico and hot and cold air masses from the interior of North America. Its climate is characterized by moderately large variations in temperature and abundant precipitation. For most of the state, summers are warm and humid while winters are cool with occasional episodes of very cold arctic air. Temperature decreases across the state in parallel with increasing elevation, averaging a 3°F decline per 1,000 feet increase in elevation. The higher elevations of the state, such as the Cumberland Plateau (average elevation of 2,000 feet) and the Smoky Mountains (peaks up to 6,000 feet), have noticeably lower average temperatures compared to the Great Valley of East Tennessee (slopes from 1,500 feet in the north to 700 feet in the south). Average minimum temperatures in January range from 22°F in Mountain City to 33°F in Memphis. Average high temperatures in the summer vary between 85°F and 90°F in western and middle Tennessee and between 80°F and 85°F in the eastern portion of the state. Historical observed extreme temperatures for the state range from -32°F in Mountain City in the winter of 1917 to 113°F in Perryville in the summer of 1930.

 

Figure 1

Observed and Projected Temperature Change

VIEW

Observed and projected changes (compared to the 1901–1960 average) in near-surface air temperature for Tennessee. Observed data are for 1900–2014. Projected changes for 2015–2100 are from global climate models for two possible futures: one in which greenhouse gas emissions continue to increase (higher emissions) and another in which greenhouse gas emissions increase at a slower rate (lower emissions). Temperatures in Tennessee (orange line) have not risen significantly since the beginning of the 20th century. Shading indicates the range of annual temperatures from the set of models. Observed temperatures are generally within the envelope of model simulations of the historical period (gray shading). Historically unprecedented warming is projected during 21st century. Less warming is expected under a lower emissions future (the coldest years being about as warm as the hottest year in the historical record; green shading) and more warming under a higher emissions future (the hottest years being about 11°F warmer than the hottest year in the historical record; red shading). Source: CICS-NC and NOAA NCEI

Tennessee has not seen a significant increase in temperatures since the beginning of the 20th century. Temperatures in Tennessee were highest in the 1920s and 1930s, followed by a substantial cooling of about 2°F by the 1960s (Figure 1). Temperatures have risen since that cool period by almost 2°F, such that the most recent decade is near the highs of the 1920s and 1930s. Because of the large cooling that occurred in the middle of the 20th century, the southeastern United States is one of the few locations globally that has experienced little to no overall warming since 1900, while the United States as a whole has warmed by about 1.5°F. The United States as a whole also cooled from the 1930s into the 1960s, but not by nearly as much as Tennessee. Potential causes for this difference in warming rates have been the subject of research, but this phenomenon has not been fully explained. However, some recent years have been very warm, including 1998 (3rd warmest), 2007 (4th warmest), and 2012 (2nd warmest). The number of extremely hot days (maximum temperature above 100°F) was highest in the 1930s and early 1950s. Since then, the number has been mostly near to below average (Figure 2). The number of very warm nights (minimum temperature above 75°F) has fluctuated around the long-term average over the last two decades (Figure 3).

 

Observed Number of Extremely Hot Days

Observed Number of Extremely Hot Days

Figure 2: The observed number of extremely hot days (annual number of days with maximum temperature above 100°F) for 1950–2014, averaged over 5-year periods; these values are averages from 19 long-term reporting stations. The number of extremely hot days has not changed much over the last 60 years, until the most recent decade, which saw a slight increase. Record high numbers occurred during the droughts of the 1930s and early 1950s. The dark horizontal line is the long-term average (1900–2014) of 2.3 days per year. Source: CICS-NC and NOAA NCEI.

 

Observed Number of Very Warm Nights

Observed Number of Very Warm Nights

Figure 3: The observed number of very warm nights (annual number of days with minimum temperatures above 75°F) for 1900–2014, averaged over 5-year periods; these values are averages from 19 long-term reporting stations. The number of very warm nights has generally been near the long-term average since 1980, with slightly above average levels for the last 5 years. The dark horizontal line is the long-term average (1900–2014) of 2.0 days per year. Source: CICS-NC and NOAA NCEI

Average annual precipitation has been mostly above average since 1990 (Figure 4). The number of extreme precipitation events (daily precipitation greater than 3 inches) has also been generally above the long-term average over the same time period. The highest 5-year average number of such events occurred during 2000–2004 (Figure 5). Summer precipitation averages 12.5 inches and exhibits no long-term trend (Figure 6). Over the entire historical period (1895–2014), the driest year on record occurred in 1941 with a statewide annual average of 36.44 inches of precipitation, while the wettest year recorded was 1957 with an annual average of 66.32 inches. The driest 5-yr period was 1939–1943 with average annual precipitation of about 44 inches and the wettest was 1971–1975, which averaged over 60 inches per year.

 

Observed Annual Precipitation

Observed Annual Precipitation

Figure 4: The observed annual precipitation for 1895–2014, averaged over 5-year periods; these values are averages from NCEI’s version 2 climate division dataset. Annual precipitation varies widely from year to year. For the most recent 5-year period (2010–2014), precipitation has been above the long-term average. The dark horizontal line is the long-term average (1895–2014) of 51.8 inches. Source: CICS-NC and NOAA NCEI.

 

Observed Number of Extreme Precipitation Events

Observed Number of Extreme Precipitation Events

Figure 5: The observed number of extreme precipitation events (annual number of events with greater than 3 inches) for 1950–2014, averaged over 5-year periods; these values are averages from 19 long-term reporting stations. Tennessee has experienced an above average number of extreme precipitation events since 1990, except for the period from 2005 to 2009. The dark horizontal line is the long-term average (1900–2014) of 0.67 days per year. Source: CICS-NC and NOAA NCEI.

 

Observed Summer Precipitation

Observed Summer Precipitation

Figure 6: The observed total annual summer precipitation for 1895–2014, averaged over 5-year periods; these values are averages from NCEI’s version 2 climate division dataset. The most recent 5-year period experienced above average precipitation. The dark horizontal line is the long-term average (1895–2014) of 12.5 inches. Source: CICS-NC and NOAA NCEI.

Extreme weather events that frequently occur in Tennessee include severe thunderstorms, flooding, tornadoes, droughts, heat and cold waves, and winter storms. The remnants of hurricanes occasionally track across the state. Since 2000, the state has received 17 major disaster declarations involving severe storms and flooding. The Flood of 2010 was characterized by record-breaking amounts of rainfall in early May. The National Weather Service reported a new 2-day rainfall record for Nashville over May 1–2, 2010 when 13.57 inches fell, shattering the previous record of 6.68 inches set on September 13–14, 1979. The entire western region and Middle Tennessee experienced “1000-year floods” with many locations receiving 10 to 20 inches of rain in a 48-hour period. Damages in Nashville alone totaled $1.5 billion.

Tennessee experiences a relatively high number of tornadoes, averaging approximately 25 tornadoes and 6 fatalities per year over the period 1985–2014. While tornadoes can occur in any month, they tend to peak in the spring. One of the most active and destructive tornado months on record for the entire United States occurred in April 2011 with a total of 542 tornadoes recorded. Tennessee reported 106 tornadoes for this month, surpassing a historical record of 42 tornadoes in April 1974.

Droughts are a regular feature of the state’s climate. In about half of the weeks since 2000, at least some portion of Tennessee has been in drought status. In 19% of the weeks, at least half of the state experienced some degree of drought conditions.

Average annual snowfall ranges from a modest 1–4 inches in southern sections to nearly a foot in the northeast, with higher amounts in the Great Smoky Mountains. Winter weather includes occasional damaging snow and ice storms. During February 9–13, 1994, a devastating ice storm struck much of the southern United States. In Tennessee, 5–8 inches of rain (much of it freezing rain) fell in some locations. About 770,000 utility customers lost power (some up to a month) and damages totaled $500 million (in 1994 dollars, second behind Mississippi). During January 22–24, 2016, snowfall of 6–12 inches fell in some parts of eastern Tennessee, with more than a foot in the Great Smoky Mountains.

Under a higher emissions pathway, historically unprecedented warming is projected by the end of the 21st century (Figure 1). Even under a pathway of lower greenhouse gas emissions, average annual temperatures are projected to most likely exceed historical record levels by the middle of the 21st century. However, there is a large range of temperature increases under both pathways, and under the lower pathway, a few projections are only slightly warmer than historical records. Continuation of the post-1980 warming trend would lead to an approximate additional warming of 1°F by 2050 and 3°F by 2100. In this case, the future warming would be on the low end of the model-simulated increases. However, under a high emissions scenario the future rate of warming is projected to increase, potentially leading to considerably larger temperature increases. Any substantial increase in temperature will lead to increased heat wave intensity but decreased cold wave intensity.

Winter and spring precipitation is projected to increase by mid-century (Figure 7), while changes in summer and fall are uncertain. The intensity of naturally-occurring droughts are likely to be more intense because higher temperatures will increase the rate of loss of soil moisture during dry spells.

 

Projected Change in Spring Precipitation

Projected Change in Spring Precipitation

Figure 7: Climate model projections of changes (%) in spring precipitation by the middle of the 21st century relative to the late 20th century under a higher emissions pathway. Hatching represents areas where the majority of climate models indicate a statistically significant change. Precipitation is projected to increase in Tennessee. Source: CICS-NC and NOAA NCEI.

Lead Authors:
Jennifer Runkle, Kenneth Kunkel
Contributing Authors:
David Easterling, Laura Stevens, Brooke Stewart, Rebekah Frankson, and Luigi Romolo
Recommended Citation:
Runkle, J., K. Kunkel, D. Easterling, L. Stevens, B. Stewart, R. Frankson, and L. Romolo, 2017: Tennessee State Summary. NOAA Technical Report NESDIS 149-TN, 4 pp.

RESOURCES

  1. Abkowitz, M., J. Camp, R. Chen, V. Dale, J. Dunn, D. Kirschke, D. de La Torre ugarte, J. Fu, J. Gilligan, Q. He, D. Larsen, E. Parish, B. Preston, J. Schwartz, A. Vergara, B. Wesh, and T. Wilbanks, 2012: Sustaining Tennessee in the face of climate change: Grand challenges and great opportunities, 72 pp. [Available online at http://www.eenews.net/assets/2012/09/13/document_cw_01.pdf]
  2. AON Benfield, 2011: United States April & May 2011 Severe Weather Outbreaks, Impact Forecasting, Severe Weather Outbreaks Event Recap Report. [Available online at http://www.aon.com/attachments/reinsurance/201106_us_april_may_severe_weather_outbreaks_recap.pdf]
  3. Borenstein, S., 2014: Tennessee second in tornado deaths nationwide, published June 15, 2014, retrieved March 17, 2015. [Available online at http://www.tennessean.com/story/weather/2014/06/15/tennessee-second-tornado-deaths-nationwide/10560407/]
  4. Knowlton, K., 2015: Climate change threatens health, National Resources Defense Council. [Available online at http://www.nrdc.org/health/climate/id.asp]
  5. Kunkel, K.E, L.E. Stevens, S.E. Stevens, L. Sun, E. Janssen, D. Wuebbles, C.E. Konrad II, C.M. Fuhrman, B.D. Keim, M.C. Kruk, A. Billet, H. Needham, M. Schafer, and J.G. Dobson, 2013: Regional Climate Trends and Scenarios for the U.S. National Climate Assessment. Part 2. Climate of the Southeast U.S., NOAA Technical Report NESDIS 142-2, 94 pp. [Available online at https://www.nesdis.noaa.gov/content/technical-reports]
  6. Lott, J.N. and M.C. Sittel, 1994: The February 1994 ice storm in the Southeastern U.S. , National Oceanic and Atmospheric Administration National Climatic Data Center, 7pp. [Available online at https://www.ncdc.noaa.gov/oa/pub/data/special/iwais96.pdf]
  7. Midwestern Regional Climate Center, cited 2016: “(1981-2010) Maps of gridded data long-term averages; Average Temp — Tennessee.” [Available online at http://mrcc.isws.illinois.edu/CLIMATE/]
  8. Midwestern Regional Climate Center, cited 2016: “January 22-24, 2016 snowstorm statistics — Tennessee”. [Available online at http://mrcc.isws.illinois.edu/CLIMATE/]
  9. NOAA, cited 2015: State Climate Extremes Committee (SCEC), Records, National Oceanic and Atmospheric Administration National Centers for Environmental Information. [Available online at http://www.ncdc.noaa.gov/extremes/scec/records]
  10. NOAA, cited 2015: Storm Events Database - State/Area: Tennessee, National Oceanic and Atmospheric Administration. [Available online at https://www.ncdc.noaa.gov/stormevents/]
  11. NOAA, cited 2015: Storm Prediction Center WCM Page, National Oceanic and Atmospheric Administration. [Available online at http://www.spc.noaa.gov/wcm/]
  12. NOAA, cited 2016: Climate at a Glance: U.S. Time Series, published October 2016, retrieved on October 18, 2016, National Oceanic and Atmospheric Administration National Centers for Environmental Information. [Available online at http://www.ncdc.noaa.gov/cag/]
  13. NOAA, cited 2016: Climate of Tennessee, National Oceanic and Atmospheric Administration. [Available online at https://ag.tennessee.edu/climate/Documents/Climate%20of%20TN.pdf]
  14. Tennessee State Library and Archives, cited 2016: Disasters in Tennessee. [Available online at http://share.tn.gov/tsla/exhibits/disasters/index.htm]
  15. Tornado History Project, cited 2016: Tornadoes in Tennessee. [Available online at http://www.tornadohistoryproject.com/tornado/Tennessee]
  16. USDA, United States Drought Monitor, cited 2015: Percent Area in U.S. Drought Monitor Categories United States Department of Agriculture. [Available online at http://droughtmonitor.unl.edu/MapsAndData/DataTables.aspx]
  17. Walsh, J., D. Wuebbles, K. Hayhoe, J. Kossin, K. Kunkel, G. Stephens, P. Thorne, R. Vose, M. Wehner, J. Willis, D. Anderson, S. Doney, R. Feely, P. Hennon, V. Kharin, T. Knutson, F. Landerer, T. Lenton, J. Kennedy, and R. Somerville, 2014: Ch. 2: Our Changing Climate. Climate Change Impacts in the United States: The Third National Climate Assessment, J. M. Melillo, T.C. Richmond, and G. W. Yohe, eds., U.S. Global Change Research Program, 19-67. http://dx.doi.org/10.7930/J0KW5CXT.
>