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Climate of San Diego, California NOAA Technical Memorandum NWS WR-270 CLIMATE OF SAN DIEGO, CALIFORNIA Revised by: Emmanuel M. Isla Steve Vanderburg Christopher Medjber Daniel Paschall September 2004 First Edition: Thomas E. Evans, III, Donald A. Halvorson-October 1998 UNITED STATES National Oceanic and National Weather Service DEPARTMENT OF COMMERCE Atmospheric Administration David L. Johnson, Assistant Donald Evans, Secretary Conrad C.. Lautenbacher Administrator for Weather Services Under Secretary and Administrator This publication has been reviewed and is approved for publication by Scientific Services Division, Western Region Delain A. Edman, Chief Scientific Services Division Salt Lake City, Utah iii TABLE OF CONTENTS PAGE I. Introduction........ ............. ............................ ............. ............. .............. ............. ............. ......... 1 II. The City of San Diego...... ............................ ............. ............. .............. ............. ............. ......... 2 III. History.. ............. ............. ............................ ............. ............. .............. ............. ............. ......... 3 IV. Temperatures...... ............. ............................ ............. ............. .............. ............. ............. ......... 4 V. Precipitation ....... ............. ............................ ............. ............. .............. ............. ............. ......... 8 VI. Wind..... ............. ............. ............................ ............. ............. .............. ............. ............. ......... 12 VII. Pressure ............. ............. ............................ ............. ............. .............. ............. ............. ......... 13 VIII. Relative Humidity ............ ............................ ............. ............. .............. ............. ............. ......... 13 IX. Air Quality......... ............. ............................ ............. ............. .............. ............. ............. ......... 14 X. Sky Cover, Clouds, Fog and Haze................. ............. ............. .............. ............. ............. ......... 15 XI. Coastal Eddy...... ............. ............................ ............. ............. .............. ............. ............. ......... 15 XII. Our Changing Climate ..... ............................ ............. ............. .............. ............. ............. ......... 16 XIII. Acknowledgments............ ............................ ............. ............. .............. ............. ............. ......... 17 XIV. References.......... ............. ............................ ............. ............. .............. ............. ............. ......... 17 iv LIST OF FIGURES, CHARTS AND TABLES LIST OF FIGURES PAGE 1. Map of San Diego County ............................ ............. ............. .............. ............. ............. ......... 19 2. Weather Station Locations of San Diego ...... ............. ............. .............. ............. ............. ........ 20 LIST OF CHARTS 1. Climograph ..................... ............................ ............. ............. .............. ............. ............. ......... 26 2. Mean Annual Temperature............................ ............. ............. .............. ............. ............. ......... 27 3. Mean Annual Max. Temperature .................. ............. ............. .............. ............. ............. ........ 28 4. Mean Annual Min. Temperature ................... ............. ............. .............. ............. ............. ........ 29 5. Normal Station Pressure... ............................ ............. ............. .............. ............. ............. ....... 52 6. Seasonal Precipitation ...... ............................ ............. ............. .............. ............. ............. ......... 56 7. Seasonal Precipitation Departure From Normal.......... ............. .............. ............. ............. ......... 57 6. Thunderstorm Days.......... ............................ ............. ............. .............. ............. ............. ......... 89 7. Annual Fog Days ............. ............................ ............. ............. .............. ............. ............. ......... 93 8. Annual Dense Fog Days... ............................ ............. ............. .............. ............. ............. ......... 96 9. Annual Haze Days............ ............................ ............. ............. .............. ............. ............. ......... 97 10. Air Quality Violation Days ........................... ............. ............. .............. ............. ............. ........ 105 LIST OF TABLES 1. Miscellaneous Means and Extremes ............. ............. ............. .............. ............. ............. ......... 21 2. Daily Normals of Temperature, Heating and Cooling Days and Precipitation ....... ............. ............................ ............. ............. .............. ............. ............. ......... 22 V PAGE 3. Temperature Readings of 100 Degrees and Higher..... ............. .............. ............. ............. ......... 30 4. Temperature Readings of 32 Degrees and Cooler....... ............. .............. ............. ............. ......... 31 5. Mean Yearly Temperatures in Descending Order....... ............. .............. ............. ............. ......... 32 6. Mean Monthly Temperatures ........................ ............. ............. .............. ............. ............. ......... 33 7. Highest and Lowest Daily Temperatures ...... ............. ............. .............. ............. ............. ......... 38 8. Pressure Statistics............. ............................ ............. ............. .............. ............. ............. ......... 50 9. Monthly and Seasonal Precipitation.............. ............. ............. .............. ............. ............. ......... 56 10. Greatest Daily Precipitation.......................... ............. ............. .............. ............. ............. ......... 64 11. Number of Consecutive Days With No Measurable Precipitation ........... ............. ............. ......... 67 12. Years that Measurable Precipitation Fell Every Month ............ .............. ............. ............. ......... 67 13. Maximum Monthly Precipitation with Four Inches or More .... .............. ............. ............. ......... 68 14. Greatest Rainfall for a Calendar Day ............ ............. ............. .............. ............. ............. ......... 69 15. Precipitation Statistics by the Month............. ............. ............. .............. ............. ............. ......... 70 16. Return Period - Maximum Precipitation ....... ............. ............. .............. ............. ............. ......... 72 17. Significant Maximum and Minimum Monthly Rainfall............ .............. ............. ............. ......... 73 18. Days With Thunderstorms ............................ ............. ............. .............. ............. ............. ......... 85 19. Number of Days With Fog Reported............. ............. ............. .............. ............. ............. ......... 90 20. Number of Days With Dense Fog Reported.. ............. ............. .............. ............. ............. ......... 94 21. Number of Days With Haze Reported........... ............. ............. .............. ............. ............. ......... 97 22. Average Daily Surfline Water Temperature for Mission Beach .............. ............. ............ ........ 100 23. Mean Monthly Wind Direction for Each Hour of the Day........ .............. ............. ............. ........ 101 24. Mean Monthly Wind Speed for Each Hour of the Day in Knots ............. ............. ............. ........ 102 25. Peak Wind Gust for Each Month of Each Year in Miles Per Hour .......... ............. ............. ........ 103 26. Number of Days Not Satisfying the Air Quality Standards in Parts of Ozone Per Hundred Million Parts of Air....... ............. ............. .............. ............. ............. ........ 104 vi THE CLIMATE OF SAN DIEGO, CALIFORNIA Updated July 2004 by Emmanuel Isla, Steve Vanderburg, Christoher Medjber, and Daniel Paschall First Edition by Thomas E. Evans, III Donald A. Halvorson I. INTRODUCTION Department of Water Resources, San Diego Flood Control District, City of San Diego The city of San Diego, California has a Water Utilities Department, U.S. Geological moderated Mediterranean climate with some Survey, Caltrans, International Boundary surprising and unique features. The Commission, San Diego Air Pollution National Weather Service has not issued a Control District and the Department of climatology of San Diego, but in 1913 the Defense. San Diego Chamber of Commerce, in cooperation with the National Weather This paper represents an effort to assemble Service (at that time known as the United the latest relevant climatological data for the States Weather Bureau), published a book city of San Diego. Within this paper, long- entitled “The Climate and Weather of San term temperature records are analyzed, Diego, California.” The climatological precipitation trends are fully discussed and stations used in the 1913 San Diego research into many other significant weather climatology and in
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