GRAPHICAL CLIMATOLOGY OF DOWNTOWN LOS ANGELES
DAILY TEMPERATURES AND RAINFALL,
BY YEAR (1921-PRESENT)
By Charles Fisk*,
Newbury Park, CA. Latest Update: 15
March 2010
The following is a visual climatology of
Downtown Los Angeles, California temperatures and precipitation, from 1921, the
earliest year of continuous available digital observations, into the present
year 2010.
Included are summary overview charts followed by 91 year-to-year
graphs from 1921 to 2010 depicting daily temperatures and rainfall.
The 1921-to-present period of record
consists of 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 2009-10 RAINFALL
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 2008-09 SEASONS)
TEMPERATURE:
DAILY MEANS & EXTREMES (FOR 1921-2008)
COMPLETE
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:
DOWNTOWN LOS ANGELES
ANNUAL MEAN TEMPERATURE HISTORY (1921-2009)
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
“Diurnal and Seasonal
Wind Variabilty for Selected Stations in Central and
Northern California Climate Regions” – American Meteorological Society 21st
Conference on Climate
Variability and Change - Phoenix, 2009. http://ams.confex.com/ams/pdfpapers/150512.pdf
“Diurnal and Seasonal Wind Variabilty for Selected Stations in Southern California
Climate Regions” – American Meteorological Society 20th Conference on Climate Variability and
Change - New Orleans, 2008. http://ams.confex.com/ams/pdfpapers/135164.pdf
“Identification of Intra-month Daily Mean Temperature
Modes Using Principal Components Analysis” – American Meteorological Society
16th Conference on Applied Climatology –
San Antonio, 2007. http://ams.confex.com/ams/pdfpapers/119632.pdf
“Principal Components Analysis of Month-to-Month Precipitation Variability
for Downtown Los Angeles (1877-8 Through 2003-4
Seasons)” – American Meteorological Society 19th Conference
on Hydrology
– San Diego, 2005.
http://ams.confex.com/ams/pdfpapers/86848.pdf
“Objective Identification of Extreme-most Anomalous
Daily Max/Min Historical Temperature Patterns Using Principal Components
Analysis” – American Meteorological Society 17th Conference
on Probability
and Statistics in the Atmospheric Sciences – Seattle, 2004.
http://ams.confex.com/ams/pdfpapers/69198.pdf
YEAR-TO-YEAR GRAPHS - INTERPRETATION
The uppermost chart
for a given year’s page (see links below) are “floating-bars” of the
daily maxima and minima. Superimposed on the bars are two line traces, the
upper one connecting 1921 to present average daily maxima, the lower one
average daily minima. The bars depict the varying diurnal, synoptic,
long-wave, and seasonal influences on temperature over time, and subjectively,
some years’ visual features can be quite interesting to look at, interpreted
physically or simply for their own sake.
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 - 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
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) – see chart
(top). 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).
REPEAT 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
through the year.
1931 - Warmest year in the historical record
up to this point.
1932 – Coo1 summer, but warmest November of
the entire history (1877-present) followed by a sharp early December cold snap.
1937 – Very cold January, highest temperature
only 61 F. Each of the year’s first 58 days colder than normal.
1938 - Torrential late February/early March rains cause
severe local flooding; 5.88” rain 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. 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).
* Member, American Meteorological
Society
mailto:CJFISK@worldnet.att.net