Graphical Climatology of Downtown Los Angeles: Daily Temperatures and Rainfall, by Year (1921 – Present)
By Charles Fisk*, Newbury Park, CA.
Latest Update: 22 Feb 2013
Note: Website is in process of redesign. No updates except  Precip. until completed.
The following is a graphical climatology of Downtown Los Angeles, California temperatures and precipitation, from 1921 through 2012. Included are summary overview charts followed by 92 year-to-year graphs depicting daily temperatures, temperature anomalies, and rainfall. The 1921-to-present period of record comprises observations from the Los Angeles Weather Bureau Office (through July 1964), the Los Angeles Civic Center (through late July 1999), and the Downtown USC Campus (late July 1999-to Present).
For the 1921-2000 period, data were accessed from the NOAA National Climatic Data Center on-line site, and from 2001 on, from the NWS Office-Los Angeles/Oxnard site (Downtown Los Angeles Climate page): http://www.weather.gov/climate/index.php?wfo=lox
CLIMATE OVERVIEW GRAPHS

RAINFALL: DOWNTOWN LOS ANGELES SEASON-TO-DATE 2012-13     **   
DOWNTOWN LOS ANGELES AVERAGE MONTHLY RAINFALL
DOWNTOWN LOS ANGELES AVERAGE MONTHLY RAINFALL FOR EL NINO, LA NINA, & NEUTRAL EPISODES
DOWNTOWN LOS ANGELES AVERAGE SEASON-TO-DATE RAINFALL CURVES FOR EL NINO, LA NINA, & NEUTRAL EPISODES
DOWNTOWN LOS ANGELES WATER YEAR RAINFALL (1877-78 THRU 2011-12 SEASONS)     
DOWNTOWN LOS ANGELES PCT. FREQUENCIES OF >=0.01 in., >=0.25 in., AND >=1.00 in. RAINFALL DAYS, BY CALENDAR DAY

TEMPERATURE:
DAILY MEANS & EXTREMES (FOR 1921-2008)

YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

CLIMOGRAMS FOR LOS ANGELES INT’L AIRPORT:

TEMPERATURE/HUMIDITY
WINDS
FLYING WEATHER/CEILINGS
FOG/HAZE
PRECIPITATION
BLOWING SAND/DUST
THUNDERSTORMS

OTHER SUMMARY CLIMATE CHARTS:

DOWNTOWN LOS ANGELES ANNUAL MEAN TEMPERATURE HISTORY (1921-2012)   **  
DOWNTOWN LOS ANGELES AVERAGE DAILY TEMPERATURE RANGES, BY CALENDAR DAY
DOWNTOWN LOS ANGELES AVERAGE DAY-TO-DAY VARIABILITY IN MEAN, MAX, & MIN TEMPERATURE, BY CALENDAR DAY
DOWNTOWN LOS ANGELES INTER-YEAR VARIABILITY (STANDARD DEVIATION) STATISTICS FOR DAILY MEAN, MAX, & MIN TEMPERATURES 

YEAR-TO-YEAR GRAPHS – INTERPRETATION
The uppermost chart for a given year’s page (accessed by the links below) are “floating-bars” of the year’s daily maxima and minima temperatures. Superimposed on the bars are two line traces, the upper one connecting 1921 to present mean daily maxima, the lower one mean daily minima. The bars depict the varying diurnal, synoptic, long-wave, seasonal, and sea-surface temperature anomaly influences on LA temperature over time, and subjectively, some years’ features can be quite interesting to look at.
The second chart down shows the day-to-day mean temperature anomalies (daily mean temperature less the corresponding long-term climatological mean). Vertical lines extending upward from the zero line indicate above average means for the day (colored red), those extending downward indicate below average daily means (colored blue). In general, the most extreme departures for Downtown Los Angeles are positive, reflecting to a large extent the occurrence of warming offshore flow episodes. In the entire 1921-present series, greatest positive departure for any given calendar day is +28 F for 6 April 1989, the most negative departure -19 F for 10 January 1949.
YEAR-TO-YEAR GRAPHS – COMPLETE SET OF LINKS
1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
The third chart down shows the second chart’s anomalies in deseasonalized (“standardized”) form. This adjusts for the fact that individual calendar days have higher or lower inherent year-to-year variability in mean temperature. For example, Downtown Los Angeles calendar day mean temperature standard deviations for the 1921-2008 period ranged from 6.73 F (29 January) to 3.37 F (4 August). To convert each of the daily temperature anomalies to a common, relative scale, they are divided by their corresponding calendar day standard deviations to create “standardized departures” or “z-scores. Those of plus or minus 3.0 occur just 0.5% of the time; nearly all of these positively signed, again reflecting extreme warming offshore flow episodes. Greatest positive departure in the record is +5.3 for 11 June 1979, greatest negative –3.4 for 22 December 1990.
The bottom chart depicts daily precipitation totals, as high as 5.88 inches (2 March 1938).
LINKS TO SOME OF THE MORE INTERESTING YEAR-TO-YEAR GRAPHS, WITH ACCOMPANYING NOTES

1921 – Wettest May in history (3.57”), and also coolest — 1921-present.
1926 – More than 7 ½” rain in April – most for any April in all history (1878-present).
1930 – Highly fluctuating temperature pattern throughout the year.
1931 – Warmest year in the historical record up to this point.
1932 – Sharp early December cold snap follows warmest November of the entire history (1877-present).
1937 – Very cold January, highest temperature only 61 F. Each of the year’s first 58 days colder than normal. Killing freezes all over SoCal.
1938 – Torrential late February/early March rains cause severe local flooding;  11.06″ rain over five days, 5.88” on 2 March.
1939 – Week-long September heat wave precedes landfall of dissipating hurricane, which drops more than 5” rain. Warmest December of entire history (1877-present).
1940-41 – Wettest July-June “water year” (32.76”) since 1883-84, and until 1977-78.
1944 – Coolest calendar year of 1921-present period. Also coolest June and July.
1948-49 – Coldest meteorological winter (December-February) and calendar month (January) of entire history. Record coldest minimum (28 F) for any day (1921-present) on 4 January.
1953 – Driest calendar year (4.08”) in all history.
1955 – Eight-day run of 100 F or higher maxima from 31 August; 110 F on 1 September.
1959 – Warmest calendar year to date.
1960-61 – Driest water year (4.85”) in all history up to this time.
1963 – Late September heat wave.
1965 – October heat wave, but more than 15” rain in November and December.
1966 – 100 F on 1 November.
1967 – Highly irregular day-to-day temperature pattern over course of year. Nearly 8 3/4” rain in November.
1969 – January wettest calendar month (14.94”) since December 1889.
1971 – Another highly irregular day-to-day temperature pattern over course of year. January experiences 95 F, February 91 F, September 106 F, and October 102 F, but December’s monthly mean ties 1916’s for lowest in history.
1971-72 – Nearly all the water year’s precipitation falls in December.
1975 – Coolest year since 1948.
1977-78 – Wettest water year (33.44”) since 1883-84 and until 2004-05.
1980 – Warmest year of entire history to date. Heavy February rains.
1981 – Another record warm year (surpasses 1980’s mark by 1.2 F). June also warmest in history.
1983 – Great El Nino year. Wettest calendar year, 1921-present (34.04”). Another record warmest year (surpasses 1981’s mark by <0.1 F).
1984 – September warmest calendar month in all history.
1985 – Warmest July in all history up to this time – 107 F on 1st.
1986 – Warmest January in all history.
1988 – 110 F on 1 September.
1989 – 106 F in April surpasses previous high mark for month by 7 F.
1990 – 112 F on 26 June sets all time high mark for any month. Late December cold spell.
1990-91 – “March Miracle” water year. Heavy late-February and March rains set in after exceptionally dry winter up to this point.
1992 – Warmest April of entire history.
1995 – More than 12 ½” rain in January. Warmest February of entire history.
1997 – Warmest meteorological Spring (March-May) of entire history. No recorded rainfall from 18 Feb through 24 Sep – 219 days.
1998 – The other great El Nino year of the 20th Century. Nearly 13 ¾” rain in February.
2001 – Coolest year since 1975.
2001-02 – Driest water year (4.42”) in all recorded history up to this point.
2004-05 – Wettest water year (37.25”) since 1883-4 and 2nd wettest in all recorded history.
2006 – Coolest March since 1962. Warmest July in all history.
2006-07 – Driest water year (3.21”) in all recorded history (27% less than 2001-02’s previous low mark).
2010 – 113 F on 27 September sets all time highest mark for any month.   

* Member, American Meteorological Society