We thank Ann Lima at the Washington State Department of Health for providing the redacted hospitalization data for western Washington and three anonymous reviewers for their thoughtful comments that improved the manuscript. Assistance from Matthew Menne and Claude Williams of the National Climatic Data Center in providing the USHCN v2 monthly adjustments is also greatly appreciated. The U.S. Department of Energy's Office of Science Innovative and Novel Computational Impact on Theory and Experiment program, the Office of Biological and Environmental Research, and the NOAA/Climate Program Office provide support for the Twentieth Century Reanalysis Project dataset. Funding for this research was provided in part by the State of Washington through funding to the Office of the Washington State Climatologist. This publication is (partially) funded by the Joint Institute for the Study of the Atmosphere and Ocean (JISAO) under NOAA Cooperative Agreement NA10OAR4320148.
Allen, S. K., and Coauthors, 2012: Managing the risks of extreme events and disasters to advance climate change adaptation: Summary for policymakers. Cambridge University Press, 19 pp.
Baars, J., , and C. Mass, 2005: Performance of National Weather Service forecasts compared to operational, consensus, and weighted model output statistics. Wea. Forecasting, 20, 1034–1047.
Barnston, A. G., , and R. E. Livezey, 1987: Classification, seasonality, and persistence of low-frequency atmospheric circulation patterns. Mon. Wea. Rev., 115, 1083–1126.
Bell, G. D., , and J. E. Janowiak, 1995: Atmospheric circulation associated with the Midwest floods of 1993. Bull. Amer. Meteor. Soc., 76, 681–695.
Beniston, M., 2004: The 2003 heat wave in Europe: A shape of things to come? An analysis based on Swiss climatological data and model simulations. Geophys. Res. Lett., 31, L02202, doi:10.1029/2003GL018857.
Bohr, G. S., 2009: Trends in extreme daily surface temperatures in California, 1950–2005. Yearb. Assoc. Pac. Coast Geogr., 71, 96–119.
Brewer, M., , C. Mass, , and B. Potter, 2012: The West Coast thermal trough: Climatology and synoptic evolution. Mon. Wea. Rev., 140, 3820–3843.
Changnon, S. A., , K. E. Kunkel, , and B. C. Reinke, 1996: Impacts and responses to the 1995 heat wave: A call to action. Bull. Amer. Meteor. Soc., 77, 1497–1506.
Chestnut, L. G., , W. S. Breffle, , J. B. Smith, , and L. S. Kalkstein, 1998: Analysis of differences in hot-weather-related mortality across 44 U.S. metropolitan areas. Environ. Sci. Policy, 1, 59–70.
Clark, R. T., , S. J. Brown, , and J. M. Murphy, 2006: Modeling Northern Hemisphere summer heat extreme changes and their uncertainties using a physics ensemble of climate sensitivity experiments. J. Climate, 19, 4418–4435.
Compo, G. P., , J. S. Whitaker, , and P. D. Sardeshmukh, 2006: Feasibility of a 100-year reanalysis using only surface pressure data. Bull. Amer. Meteor. Soc., 87, 175–190.
Compo, G. P., and Coauthors, 2011: The Twentieth Century Reanalysis Project. Quart. J. Roy. Meteor. Soc., 137, 1–28, doi:10.1002/qj.776.
Davis, R. E., , P. C. Knappengerger, , P. J. Michaels, , and W. M. Novicoff, 2003: Changing heat-related mortality in the United States. Environ. Health Perspect., 111, 1712–1718.
Davis, R. E., , P. C. Knappengerger, , P. J. Michaels, , and W. M. Novicoff, 2004: Seasonality of climate–human mortality relationships in US cities and impacts of climate change. Climate Res., 26, 61–76.
Di Lorenzo, E., and Coauthors, 2008: North Pacific gyre oscillation links ocean climate and ecosystem change. Geophys. Res. Lett., 35, L08607, doi:10.1029/2007GL032838.
Gershunov, A., , D. R. Cayan, , and S. F. Iacobellis, 2009: The great 2006 heat wave over California and Nevada: Signal of an increasing trend. J. Climate, 22, 6181–6203.
Gershunov, A., , Z. Johnston, , H. G. Margolis, , and K. Guirguis, 2011: The California heat wave 2006 with impacts on statewide medical emergency: A space–time analysis. Geogr. Res. Forum, 31, 6–31.
Guirguis, K., , A. Gershunov, , R. Schwartz, , and S. Bennett, 2011: Recent warm and cold daily winter temperature extremes in the Northern Hemisphere. Geophys. Res. Lett., 38, L17701, doi:10.1029/2011GL048762.
Hajat, S., and Coauthors, 2006: Impact of high temperatures on mortality: Is there an added heat wave effect? Epidemiology, 17, 632–638.
Hoshiko, S., , P. English, , D. Smith, , and R. Trent, 2009: A simple method for estimating excess mortality due to heat waves, as applied to the 2006 California heat wave. Int. J. Public Health, 55, 133–137, doi:10.1007/s00038-009-0060-8.
Jackson, J. E., and Coauthors, 2010: Public health impacts of climate change in Washington State: Projected mortality risks due to heat events and air pollution. Climatic Change, 102, 159–186.
Kalkstein, L. S., , and R. E. Davis, 1989: Weather and human mortality: An evaluation of demographic and interregional responses in the United States. Ann. Assoc. Amer. Geogr., 79, 44–64.
Kendall, M. G., 1955: Rank Correlation Methods. 2nd. ed. Griffin, 196 pp.
Kunkel, K. E., , S. A. Changnon, , B. C. Reinke, , and R. W. Arritt, 1996: The July 1995 heat wave in the Midwest: A climatic perspective and critical weather factors. Bull. Amer. Meteor. Soc., 77, 1507–1518.
Kunkel, K. E., , X.-Z. Liang, , and J. Zhu, 2010: Regional climate model projections and uncertainties of U.S. summer heat waves. J. Climate, 23, 4447–4458.
Lyon, B., 2009: Southern Africa summer drought and heat waves: Observations and coupled model behavior. J. Climate, 22, 6033–6046.
McGeehin, M. A., , and M. Mirabelli, 2001: The potential impacts of climate variability and change on temperature-related morbidity and mortality in the United States. Environ. Health Perspect., 109 (Suppl. 2), 185–189.
Meehl, G. A., , and C. Tebaldi, 2004: More intense, more frequent, and longer lasting heat waves in the 21st century. Science, 305, 994–997.
Menne, M. J., , C. N. Williams Jr., , and R. S. Vose, 2009: The U.S. Historical Climatology Network monthly temperature data, version 2. Bull. Amer. Meteor. Soc., 90, 993–1007.
Mims, F. M., , L. H. Chambers, , and D. R. Brooks, 2011: Measuring total column water vapor by pointing an infrared thermometer at the sky. Bull. Amer. Meteor. Soc., 92, 1311–1320.
National Oceanic and Atmospheric Administration, cited 2012: What is a heat index? Know when you just can't sweat it out. [Available online at http://www.noaa.gov/features/02_monitoring/heatindex.html.]
Naughton, M. P., and Coauthors, 2002: Heat-related mortality during a 1999 heat wave in Chicago. Amer. J. Prev. Med., 22, 221–227.
Office of the Washington State Climatologist, cited 2012: N.W. temperature, precipitation, & SWE trend analysis. [Available online at http://www.climate.washington.edu/trendanalysis/.]
Quayle, R. G., , D. R. Easterling, , T. R. Karl, , and P. Y. Hughes, 1991: Effects of recent thermometer changes in the cooperative station network. Bull. Amer. Meteor. Soc., 72, 1718–1723.
Reid, C. E., , M. S. O'Neill, , C. J. Gronlund, , S. J. Brines, , D. G. Brown, , A. V. Diez-Roux, , and J. Schwartz, 2009: Mapping community determinants of heat vulnerability. Environ. Health Perspect., 117, 1730–1736.
Salathé, E. P., , R. Steed, , C. F. Mass, , and P. Zahn, 2008: A high-resolution climate model for the U.S. Pacific Northwest: Mesoscale feedbacks and local responses to climate change. J. Climate, 21, 5708–5726.
Semenza, J. C., , C. H. Rubin, , K. H. Falter, , J. D. Selaniko, , D. Flanders, , H. L. Howe, , and J. L. Wilhelm, 1996: Heat-related deaths during the July 1995 heat wave in Chicago. N. Engl. J. Med., 335, 84–90.
Sheridan, S. C., , and L. S. Kalkstein, 2004: Progress in heat watch–warning system technology. Bull. Amer. Meteor. Soc., 85, 1931–1941.
Solomon, S., , D. Qin, , M. Manning, , M. Marquis, , K. Averyt, , M. M. B. Tignor, , H. L. Miller Jr., , and Z. Chen, Eds., 2007: Climate Change 2007: The Physical Science Basis. Cambridge University Press, 996 pp.
Vose, R. S., , R. Easterling, , and B. Gleason, 2005: Maximum and minimum temperature trends for the globe: An update through 2004. Geophys. Res. Lett., 32, L23822, doi:10.1029/2005GL024379.