Robert J. Renard
Nat'l Wea Serv Climatological Station
Monterey, California 93940
SUMMARY of the SEPTEMBER 1996 WEATHER ON THE MONTEREY PENINSULA
General: September 1996 temperatures were below normal, although there was
considerable variability. Rainfall was light; while the number of fog
days and average wind speed were near seasonal expectation.
Temperature: There was considerable variation in temperature during
September 1996, but overall temperatures averaged below normal both by day
and night. The mean daily maximum of 71.2F is 0.6F below normal,
largely due to a strong negative anomaly in the last nine cloudy/foggy
days of the month, averaging -9F.
The 58F maximum on 24 September is 15oF below normal and tied the
record (set in 1962) for the coldest maximum of the date. It is also the
only September day with a maximum in the 50's since 1975 (on 7 September).
On 25 September the 61F (13F below normal) was within a degree of tieing
the coldest temperature for the date (set in 1974). The two minor
"heat-waves", 6-8 and 17-21 September, helped to balance the late-month
coolness. High for the month, 88F, was recorded on 7 September.
For the minimums, it was negative anomalies almost all the way
through the month. Only two September nights were above normal
(13, 15 September). The month's lowest, 48F, was observed on 5 September.
The average minimum of 51.0F is 1.9F below normal and represents the
fourth coolest average minimum on record for September (45 years of
record). The average minimum was 48.6F in September 1995. Also, there
were twelve September minimums of 50F or lower, a record since 13 such
days in September 1970. September's overall average temperature of 62.3F
is 1.2F below normal.
Precipitation: The 0.04" that fell mostly as drizzle during the
month classifies September 1996 as a month with light rainfall. 0.29" is
normal. As much as 3.14" has fallen in September, namely in 1959, but
less than .05" has fallen in one-third of the last 45 September's. Last
September's trace (along with September 1987) was at least a 45-year
record for scant September rainfall.
Some areas in northwest California registered rainfall over an inch
the past month due to several unusually strong winter-like fronts
mid-month, the same ones that netted only 0.04" as they passed the
Monterey Climate Station while weakening on their way south and east.
Rainfall for the rain-year 1996/97 (i.e., from 1 July ) now stands at
0.12" compared to 0.46" normal. Only 0.05" had fallen in this period last
year, i.e., between 1 July and 30 September 1995. No thunderstorms in
September 1996 even though September thunderstorm frequency is higher than
any month f rom April through November, due mostly to the infrequent
northward surges of warm moist air from subtropical North Pacific waters
off the Mexican coast.
Wind: The average hourly wind at the Monterey Peninsula Airport is 6.0
miles per hour (mph) for September 1996, which nearly equals the recent
five-year September average of 5.9 mph. Gustiness was minimal during the
month. The Naval Postgraduate School's Ft. Ord site recorded 24 mph on 8
September, as the month's maximum gust.
Fog: Fog-day frequency in September 1996 was slightly above normal namely
20 days vs. 18 normal. The duration and intensity of the September fog
episodes this year appear to be well above the norm. Fog-day frequency
has been at or above the 33-year average the past twelve months with April
1996 being an exception. If the "fog season" can be regarded as the
months with fog-day frequency 15 or more days per month, then the fog
season runs from about early June to mid-October, thus the fog season is
(should be!) behind us for this year.
Comparative Weather Data
for Stations on/near the Monterey Peninsula and Salinas
September 1996
Following are comparative figures from seven local observation sites:
1) the National Weather Service Climate Station (NWSCS), (elevation 385')
located in the western hilly section of Monterey; 2) the National Weather
Service Forecast Office (NWSFO) site (elevation 122'), located in the flat
area of eastern Monterey, on the NPS Annex grounds adjacent to Airport;
3) the Naval Postgraduate School Campus (NPS), Monterey; 4) the Ft. Ord
site (Ft. Ord (NPS)) (elevation 167') located just northwest of the Marina
Municipal Airport (formerly Fritschie Field). This is the site of the
Naval Postgraduate School's wind profiler (managed by Department of
Meteorology); 5) Site SE end of Marina, located about 2 « miles ESE of
Monterey Bay (elevation 80'); 6) Carmel Valley site (CV) near Village
(elevation 500'); south facing slope; 7) SW Salinas (SAL) vicinity of
W. Blanco Rd. within « mile of S. Main St.
Location Temperature (oF) Precipitation Wind
Avg. Highest Avg. Lowest (inches) (mph)
Max. Min. Sept this yr "Norm" Max Ave
(1 Jul-30 Sept)
1) NWSCS:
71.2 88 51.0 48 a0.04 0.12 0.46@ -- --
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2) NWSFO:
71.0 78 51.4 47 b0.02 0.03 -- -- 6.0*
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3) NPS:
69.4 80 51.2 46 c0.03 0.05 0.38# -- --
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4) Ft. Ord (NPS):
67.0 80 48.5 44 d 0.03 0.04 -- 24 7.7
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5) Marina:
67.7 78 50.3 44 e0.04 0.06 0.33& -- --
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6) CV:
80.0 93 47.8 41 ftrace trace 0.38# -- --
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7) SAL:
74.8 88 50.0 43 g0.06 0.08 0.20% -- --
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FOOTNOTES:
observations for precipitation:
a,e = 6 PM b,d = midnight c = 4 PM f, g = 8 AM
(NOTE: for f, g: 24-h rainfall measured 8 AM, first day of the month
counts for previous month)
* = average hourly Airport winds in period 6 AM to 11 PM.
@ = 45-year average # = 39-year average % = 10-year average
& = 14-year average
90-Day Temperature and Precipitation Outlook for the Central Coast: The
National Weather Service 90-day outlook for October through December
indicates near to above climatological values of temperature in November,
otherwise climatology is the preferred estimate. Rainfall expectation is
for near to below normal amounts for the latter part of the three-month
period, otherwise climatology is indicated as the preferred category.
Following are the normals for the National Weather Service Climate
Station (45-year data base).
Rainfall Normal Max/Min Temps
October 0.77" October 70.6/51.1
November 2.26" November 65.5/47.1
December 2.94" December 60.8/43.6