ISMCS Station Climatic Narrative for San Diego
The city of San Diego is located on San Diego Bay
in the southwest corner of southern California.
The prevailing winds and weather are tempered by
the Pacific Ocean, with the result that summers
are cool and winters warm in comparison with other
places along the same general latitude.
Temperatures of freezing or below have rarely
occurred at the station since the record began
in 1871, but hot weather, 90 degrees or above, is
more frequent.
Dry easterly winds sometimes blow in the vicinity
for several days at a time, bringing temperatures
in the 90s and at times even in the 100s in the
eastern sections of the city and outlying suburbs.
At the National Weather Service station itself,
however, there have been relatively few days on
which 100 degrees or higher was reached.
As these hot winds are predominant in the fall,
highest temperatures occur in the months of
September and October. Records show that over 60
percent of the days with 90 degrees or higher have
occurred in these two months. High temperatures
are almost invariably accompanied by very low
relative humidities, which often drop below 20
percent and occasionally below 10 percent.
A marked feature of the climate is the wide
variation in temperature within short distances.
In nearby valleys daytimes are much warmer in
summer and nights noticeably cooler in winter, and
freezing occurs much more frequently than in the
city. Although records show unusually small daily
temperature ranges, only about 15 degrees between
the highest and lowest readings, a few miles
inland these ranges increase to 30 degrees or
more.
Strong winds and gales associated with Pacific, or
tropical storms, are infrequent due to the
latitude.
The seasonal rainfall is about 10 inches in the
city, but increases with elevation and distance
from the coast. In the mountains to the north
and east the average is between 20 and 40 inches,
depending on slope and elevation. Most of the
precipitation falls in winter, except in the
mountains where there is an occasional
thunderstorm. Eighty-five percent of the
rainfall occurs from November through March, but
wide variations take place in monthly and seasonal
totals. Infrequent measurable amounts of hail
occur in San Diego, but snow is practically
unknown at the Weather Service Office location.
In each occurrence of snowfall only a trace was
recorded officially, but in some locations amounts
up to or slightly exceeding a half-inch fell, and
remained on the ground for an hour or more.
As on the rest of the Pacific Coast, a dominant
characteristic of spring and summer is the
nighttime and early morning cloudiness. Low
clouds form regularly and frequently extend inland
over the coastal valleys and foothills, but they
usually dissipate during the morning and the
afternoons are generally clear.
Considerable fog occurs along the coast, but the
amount decreases with distance inland. The fall
and winter months are usually the foggiest.
Thunderstorms are rare, averaging about three a
year in the city. Visibilities are good as a
rule. The sunshine is plentiful for a marine
location, with a marked increase toward the
interior.
--------------------------------------------------------------
Percent Frequency Daily PRECIPITATION AMOUNTS for Lindbergh Field
POR: : 1948-1990
PERCENT TOTAL TOTAL
OF DAYS NO. PRECIP
WITH OF (INCHES)
INCHES AMOUNTS OBS MEAN HI LOW
NONE TRACE .01 <=.05 <=.10 <=.25 <=.50 <=1.0 <=2.5 <=5.0 <=10.0 <=20.0 >20.0 >=.01
JAN 71.3 6.5 2.0 4.7 3.4 4.1 4.1 2.6 1.2 .1 0 0 0 22.1 1333 1.95 5.95 T
FEB 72.7 8.2 2.2 3.2 3.4 4.6 2.1 2.9 .8 0 0 0 0 19.1 1203 1.43 5.40 0
MAR 70.0 8.7 2.3 4.1 3.5 4.8 3.2 2.6 .9 0 0 0 0 21.3 1333 1.69 6.57 T
APR 74.7 10.4 2.8 3.6 2.6 2.9 1.7 .9 .4 0 0 0 0 14.9 1290 .79 3.71 T
MAY 79.1 13.8 2.3 2.4 1.1 .6 .6 .1 .1 0 0 0 0 7.1 1333 .20 1.79 0
JUN 83.3 13.5 1.2 1.1 .3 .3 .3 0 0 0 0 0 0 3.3 1290 .06 .87 0
JUL 92.3 6.6 .5 .4 .2 .1 0 0 0 0 0 0 0 1.1 1333 .01 .19 0
AUG 93.0 5.3 .4 .5 .2 .3 .1 .2 .1 0 0 0 0 1.7 1333 .10 2.13 0
SEP 88.1 7.8 .5 1.5 .6 .7 .5 .3 0 0 0 0 0 4.1 1290 .19 1.90 0
OCT 85.7 6.9 1.6 2.1 .7 1.7 .5 .9 0 0 0 0 0 7.4 1333 .38 1.76 0
NOV 78.8 5.6 2.0 3.1 1.9 3.1 3.2 1.6 .9 0 0 0 0 15.7 1290 1.24 5.82 0
DEC 76.9 5.9 1.5 3.6 2.4 3.8 3.3 1.7 .8 0 0 0 0 17.1 1330 1.41 6.60 .02
ANN 80.5 8.3 1.6 2.5 1.7 2.2 1.6 1.1 .4 * 0 0 0 11.2 15691 9.46 19.41 3.41
* = PERCENT < .05
T = ZERO PRECIP, SNOWFALL OR SNOW DEPTH MEASURED BUT A TRACE WAS NOTED
+ = ANNUAL HI AND LOW VALUES ARE DERIVED FROM ANNUAL TOTALS
# = EXCESSIVE MISSING DATA - VALUE NOT COMPUTED
--------------------------------------------------------------
Cumulative Percent Frequency Daily MINIMUM TEMPERATURES at Lindbergh Field
POR: : 1948-1990
Temp(F) JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANN
>=75 0 0 0 0 0 0 .3 1.1 1.6 0 0 0 .2
>=70 0 0 0 0 0 .9 9.2 15.4 11.6 .7 0 0 3.2
>=65 0 0 0 .2 2.0 12.1 55.2 74.5 51.9 16.1 .4 0 17.9
>=60 1.7 1.4 2.3 10.8 36.5 76.1 97.6 99.6 92.0 55.9 9.3 1.4 40.6
>=55 13.4 17.6 30.5 61.0 89.4 99.1 100 100 99.8 90.6 42.9 13.1 63.4
>=50 41.3 51.5 72.3 93.4 99.5 100 100 100 100 99.2 79.2 39.2 81.4
>=45 74.7 87.1 96.0 99.7 100 100 100 100 100 99.9 97.3 81.3 94.7
>=40 94.8 98.3 99.9 100 100 100 100 100 100 100 99.8 96.5 99.1
>=35 99.5 100 100 100 100 100 100 100 100 100 100 99.8 99.9
>=30 99.9 100 100 100 100 100 100 100 100 100 100 100 100
>=25 100 100 100 100 100 100 100 100 100 100 100 100 100
MEAN 48.2 49.8 52.0 55.1 58.3 61.4 65.1 66.5 64.8 60.1 53.4 48.6 57.0
STDV 5.4 4.7 4.1 3.5 3.0 2.8 3.1 3.0 3.9 4.3 4.6 4.8 7.5
#OBS 1333 1203 1333 1290 1333 1290 1333 1332 1290 1333 1290 133015690
* = PERCENT < .05
# = EXCESSIVE MISSING DATA - VALUE NOT COMPUTED
--------------------------------------------------------------
Cumulative Percent Frequency Daily MAXIMUM TEMPERATURES at Lindbergh Field
POR: : 1948-1990
Temp(F) JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANN
>=110 0 0 0 0 0 0 0 0 .1 0 0 0 *
>=105 0 0 0 0 0 0 0 0 .2 .1 0 0 *
>=100 0 0 0 0 0 .2 0 0 .8 .4 0 0 .1
>=95 0 0 0 .2 .1 .5 .2 .1 1.6 1.1 .2 0 .3
>=90 0 0 .2 .7 .6 1.4 .7 .5 4.2 2.9 1.0 0 1.0
>=85 .3 .7 .5 1.9 1.5 2.0 3.9 4.6 10.7 7.6 3.6 .4 3.1
>=80 4.1 4.0 2.8 5.2 3.5 5.5 17.3 24.7 25.7 14.9 9.8 3.2 10.1
>=75 9.8 10.5 8.2 10.9 9.1 17.9 63.2 79.1 61.9 35.7 22.1 10.5 28.4
>=70 22.1 24.5 20.4 29.5 37.9 70.2 98.4 99.8 97.5 84.2 45.5 26.7 54.9
>=65 47.9 55.4 58.7 77.8 92.9 98.8 100 100 100 99.4 86.7 60.1 81.6
>=60 85.4 91.3 96.3 99.4 99.9 100 100 100 100 100 99.4 90.3 96.8
>=55 98.5 99.6 100 100 100 100 100 100 100 100 100 99.5 99.8
>=50 99.8 100 100 100 100 100 100 100 100 100 100 100 100
>=45 100 100 100 100 100 100 100 100 100 100 100 100 100
MEAN 65.3 66.2 66.3 68.2 69.2 71.7 76.1 77.5 77.1 74.2 70.5 66.5 70.8
STDV 6.2 5.9 5.2 5.4 4.3 4.6 3.9 3.7 5.7 5.9 6.2 5.9 6.8
#OBS 1333 1203 1333 1290 1333 1290 1333 1333 1290 1333 1290 133015691
* = PERCENT < .05
# = EXCESSIVE MISSING DATA - VALUE NOT COMPUTED
--------------------------------------------------------------
San Diego Lindbergh Field Summary of Various Climate Factors
POR: (HOURLY): 1948-1990
TEMPERATURE (DEG F)| PRECIPITATION (INCHES) (^) |REL HUM|VAP|DEW| PR |WIND (KTS) | | MEAN NO. OF DAYS WITH (&)
MEANS |EXTREME| PRECIP. |SNOWFALL (@)|PERCENT|PR |PT.| ALT| |SKY|PRECIP.|SNOW- | | | TEMP (DEG F)
| | | | | | | |24H| | |24H| (LST) |IN.|(F)| FT.|PREVAIL|MAX|CVR|INCHES |FALL(")|TH |FOG|MAX|MAX|MIN|MIN
MAX|MIN|AVG|MAX|MIN| MEAN| MAX| MIN|MAX|MEAN|MAX|MAX| AM| PM|HG.| | $ |DIR|SPD|GST| + | >=| >=| >=| >=|STM| * | >=| >=| <=| <=
| 07| 16| |.01|.50|.10|1.5| | 90| 70| 32| 10
JAN 65 48 57 88 29 1.9 5.9 T 2.6 T T T 70 57 .28 43 20 NW 7 56 CLR 7 1 0 0 # 10 0 7 # 0
FEB 66 50 58 88 36 1.4 5.4 0 1.7 0 0 0 72 58 .30 45 20 WNW 8 45 CLR 5 1 0 0 # 9 0 7 0 0
MAR 66 52 59 93 39 1.7 6.6 T 2.1 0 0 0 73 59 .32 47 25 WNW 9 46 OVR 7 1 0 0 # 7 # 6 0 0
APR 68 55 62 98 44 .8 3.7 T 1.4 0 0 0 72 59 .36 50 20 WNW 9 37 OVR 4 # 0 0 # 6 # 9 0 0
MAY 69 58 64 96 48 .2 1.8 0 1.5 0 0 0 73 63 .40 53 20 WNW 8 35 OVR 2 # 0 0 # 6 # 12 0 0
JUN 72 61 67 101 51 .1 .9 0 .5 0 0 0 77 66 .46 57 20 WNW 8 32 OVR 1 0 0 0 # 7 # 21 0 0
JUL 76 65 71 95 55 T .2 0 .1 0 0 0 79 65 .54 61 20 WNW 8 26 OVR # 0 0 0 # 6 # 31 0 0
AUG 77 66 72 98 58 .1 2.1 0 1.4 0 0 0 79 66 .56 62 20 WNW 8 29 OVR 1 # 0 0 # 6 # 31 0 0
SEP 77 65 71 111 51 .2 1.9 0 .9 0 0 0 78 65 .53 61 25 WNW 8 38 CLR 1 # 0 0 # 8 1 29 0 0
OCT 74 60 67 107 43 .4 1.8 0 1.0 0 0 0 74 63 .44 55 20 WNW 8 35 CLR 2 # 0 0 # 11 1 26 0 0
NOV 71 53 62 97 38 1.2 5.8 0 2.0 0 0 0 69 60 .33 48 20 WNW 8 42 CLR 5 1 0 0 # 10 # 14 0 0
DEC 66 49 58 88 34 1.4 6.6 T 2.1 T T T 68 58 .28 43 25 NW 7 38 CLR 5 1 0 0 # 11 0 8 0 0
ANN 71 57 64 111 29 9.5 19.4 3.4 2.6 T T T 74 62 .39 52 30 WNW 8 56 OVR 40 6 0 0 5 97 4 201 # 0
POR 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 21 43 43 43 43 43 43 43 43 43 43 43
T = TRACE AMOUNTS ( < .05 < .5 INCHES
# = MEAN NO. DAYS < .5 DAYS
$ = PRESSURE ALTITUDE IN TENS OF FEET (I.E. 50 = 500 FEET)
@ = NAVY STATIONS REPORT HAIL AS SNOWFALL; ALSO NWS FROM JULY,1948 - DEC.,1955
+ = THE PREDOMINANT SKY CONDITION
* = VISIBILITY IS NOT CONSIDERED
& = ANN TOTALS MAY NOT EQUAL SUM OF MONTHLY VALUES DUE TO ROUNDING
^ = 24 HR MAX PRECIP AND SNOWFALL ARE DAILY TOTALS (MID-NIGHT TO MID-NIGHT)
I = EXCESSIVE MISSING DATA - VALUE NOT COMPUTED
" = INCHES
--------------------------------------------------------------
Number of Days per Month of PRECIPITATION & OBSTRUCTION TO VISION
for San Diego Lindbergh Field
POR: (HOURLY): 1948-1990
MEAN NO. OF DAYS WITH (&) |
PRECIPITATION | OBSTR TO VISION |
|FRZ | |HAIL| |SMOK|BLOW|DUST| OBS|
R/DZ|R/DZ|SNOW|/SLT|PRCP|HAZE|SNOW|SAND| VIS|
JAN 9 0 # # 9 11 0 0 14
FEB 8 0 0 # 8 10 0 0 14
MAR 9 0 0 # 9 9 0 0 12
APR 8 0 0 # 8 8 0 0 10
MAY 6 0 0 0 6 10 0 0 11
JUN 5 0 0 0 5 13 0 0 15
JUL 2 0 0 0 2 17 0 0 17
AUG 2 0 0 0 2 16 0 0 17
SEP 4 0 0 # 4 16 0 0 17
OCT 4 0 0 # 4 16 0 0 18
NOV 6 0 0 # 6 13 0 0 16
DEC 7 0 # # 7 13 0 0 16
ANN 70 0 # # 70 152 0 0 177
POR 42 42 42 42 42 42 42 42 42
& = ANN TOTALS MAY NOT EQUAL SUM OF MONTHLY VALUES DUE TO ROUNDING
I = EXCESSIVE MISSING DATA - VALUE NOT COMPUTED
# = MEAN NO. DAYS < .5 DAYS
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