STATION:  SAN FRANCISCO INTERNATIONAL AIRPORT (KSFO), CA

CLIMATOLOGICAL SUMMARY.  Period of Record: Jul 1996 to Dec 2008

Summaries based on unedited daily ASOS data.  Errors may be present.

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TEMPERATURE (F)     |   Jan   Feb   Mar   Apr   May   Jun   Jul   Aug   Sep   Oct   Nov   Dec |   Year
                    |                                                                         |
Avg Max Temp        |  56.2  58.8  62.2  63.5  67.3  70.0  71.3  72.3  73.4  69.8  62.6  57.1 |   65.4
Avg Min Temp        |  44.7  46.2  47.5  48.9  52.1  53.8  55.6  56.5  56.0  52.9  49.3  45.1 |   50.7
Avg Temperature     |  50.5  52.5  54.9  56.2  59.7  61.9  63.4  64.4  64.7  61.4  56.0  51.1 |   58.1
                    |                                                                         |
Extremes:           |                                                                         |
    Extreme Max Temp|    81    74    83    90    96   105    97    94    95    94    79    80 |    105
                    |                                                                         |
    Date of Ext-Day |    05    27    11    26    15    14    22    09    12    08    02    18 |
               -Year|  2000  2002  2005  2004  2008  2000  2006  2002  2003  1996  1997  2005 |
                    |                                                                         |
    Extreme Min Temp|    32    36    37    39    44    47    50    51    49    43    37    31 |     31
                    |                                                                         |
    Date of Ext-Day |    14    08    11    09    01    07    10    15    16    31    30    21 |
               -Year|  2007  2003  2006  1999  2008  2008  1998  1996  2006  2002  2004  1998 |
                    |                                                                         |
Heating Degree Days |   450   353   316   268   182   113    70    51    59   131   272   430 |   2694
Cooling Degree Days |     0     0     1     4    17    20    21    33    49    18     1     0 |    165
                    |                                                                         |
Avg Number of Days: |                                                                         |
    Max Temp >= 90  |   0.0   0.0   0.0   0.1   0.6   0.8   0.2   0.5   1.6   0.2   0.0   0.0 |    4.0
    Max Temp >= 75  |   0.1   0.0   1.8   2.5   4.4   5.2   5.8   7.9  10.0   7.2   0.8   0.1 |   45.7
    Max Temp <= 32  |   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0 |    0.0
                    |                                                                         |
    Min Temp <= 32  |   0.1   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.3 |    0.4
    Min Temp <= 20  |   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0 |    0.0
    Min Temp  <= 0  |   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0 |    0.0
                    |                                                                         |
Avg Dew Point Temp  |  44.5  45.4  45.8  45.7  48.7  50.5  53.6  54.6  53.4  49.9  48.4  44.6 |   48.8
Avg Wet Bulb Temp   |  47.5  48.8  49.8  50.3  53.2  54.9  57.1  58.0  57.5  54.5  51.9  48.1 |   52.6
                    |                                                                         |
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                    |                                                                         |
Avg Sea Level Pres  | 30.14 30.09 30.08 30.05 30.00 29.95 29.96 29.95 29.92 30.01 30.10 30.14 |  30.03
(Inches of Mercury) |                                                                         |
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                    |                                                                         |
WEATHER             |   Jan   Feb   Mar   Apr   May   Jun   Jul   Aug   Sep   Oct   Nov   Dec |   Year
See disclaimer below|                                                                         |
                    |                                                                         |
Avg Number of Days: |                                                                         |
    Thunderstorms   |   0.2   0.7   0.3   0.4   0.1   0.0   0.1   0.1   0.4   0.1   0.3   0.4 |    3.0
    Heavy Fog       |   1.8   0.8   0.3   0.1   0.0   0.0   0.0   0.0   0.2   0.5   1.0   1.2 |    5.8
    Fog             |  20.6  15.5  11.8  10.0   7.9   5.7   4.7   5.2   5.0   9.3  15.3  18.0 |  129.0
    Hail            |   0.2   0.1   0.1   0.2   0.1   0.0   0.0   0.0   0.0   0.0   0.1   0.1 |    0.7
                    |                                                                         |
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                    |                                                                         |
PRECIPITATION (In)  |   Jan   Feb   Mar   Apr   May   Jun   Jul   Aug   Sep   Oct   Nov   Dec |   Year
                    |                                                                         |
Average Monthly     |  4.16  4.61  1.86  1.62  0.50  0.08  0.00  0.05  0.06  0.82  2.32  4.82 |  20.90
                    |                                                                         |
Maximum Daily       |  2.54  2.92  0.94  1.31  0.49  0.18  0.01  0.56  0.13  1.65  1.58  2.60 |   2.92
                    |                                                                         |
    Date of Ext-Day |    25    02    05    12    27    03    16    19    09    19    08    29 |
               -Year|  2008  1998  2006  2003  1998  1999  2001  1997  1999  2004  2002  2003 |
                    |                                                                         |
Avg Number of Days: |                                                                         |
    >= 0.01         |  14.3  12.9   9.3   7.0   3.4   1.1   0.2   0.5   1.3   3.6   9.2  12.6 |   75.4
    >= 0.10         |   7.7   8.6   5.3   4.3   1.8   0.4   0.0   0.1   0.2   1.5   4.4   7.6 |   42.0
    >= 0.25         |   4.8   6.0   2.8   2.6   0.6   0.0   0.0   0.1   0.0   0.9   3.0   5.5 |   26.3
    >= 0.50         |   2.6   3.2   1.2   0.8   0.0   0.0   0.0   0.1   0.0   0.5   1.5   3.1 |   13.0
    >= 1.00         |   1.0   1.2   0.0   0.1   0.0   0.0   0.0   0.0   0.0   0.2   0.5   1.2 |    4.3
                    |                                                                         |
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                    |                                                                         |
WIND (MPH)          |   Jan   Feb   Mar   Apr   May   Jun   Jul   Aug   Sep   Oct   Nov   Dec |   Year
                    |                                                                         |
Daily Avg Wind Speed|   6.7   8.3  10.2  12.4  13.5  13.9  12.7  12.2  10.4   9.0   7.0   7.2 |   10.3
Daily Avg Max 2-Min |  18.1  21.4  23.7  26.1  26.6  27.1  24.6  24.5  23.0  21.8  18.7  19.0 |   22.9
Daily Avg Peak Gust |  21.9  25.7  28.2  30.7  31.5  32.2  29.2  28.9  27.1  25.8  22.3  23.3 |   27.2
                    |                                                                         |
Maximum Daily Avg   |  25.1  26.6  22.8  27.6  26.5  28.6  21.2  23.0  22.0  25.3  21.0  27.5 |   28.6
                    |                                                                         |
Maximum 2-Minute Avg|    54    60    46    48    46    47    40    38    39    45    51    48 |     60
                    |                                                                         |
Date of Max 2min-Day|    04    27    16    19    12    05    31    16    16    29    07    15 |
               -Year|  2008  2006  2000  2008  1999  2005  2006  2007  2003  2003  2002  2002 |
                    |                                                                         |
Maximum Peak Gust   |    68    71    51    58    54    58    49    48    52    52    66    64 |     71
                    |                                                                         |
Date of Max Gust-Day|    04    27    16    19    12    07    06    16    16    29    07    01 |
               -Year|  2008  2006  2000  2008  1999  2004  2005  2007  2003  2003  2002  2005 |
                    |                                                                         |
Avg Number of Days: |                                                                         |
   Peak Gust >=30   |   5.9   7.9  11.5  15.6  18.5  19.0  14.6  13.7   7.5   7.1   5.2   7.3 |  133.9
   Peak Gust >=40   |   1.8   3.2   2.0   3.5   3.6   3.9   1.0   0.6   0.5   0.9   1.3   3.1 |   25.6
   Peak Gust >=50   |   0.6   0.8   0.1   0.5   0.3   0.7   0.0   0.0   0.1   0.1   0.2   1.3 |    4.7
                    |                                                                         |
   Max 2-Minute >=30|   2.8   4.3   5.0   7.5   8.2   9.2   3.6   3.5   2.3   2.2   2.0   0.0 |   50.7
   Max 2-Minute >=40|   0.5   1.0   0.2   0.8   0.8   1.3   0.1   0.0   0.0   0.2   0.2   0.0 |    5.1
                    |                                                                         |
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Observations of WEATHER may me innacurate due to early ASOS inconsistancies.  Average days
with Thunderstorms may be low due to early mis-detection.

Heavy Fog = Visibility less than or equal to 1/4 mile.
Fog = Visibility greater than 1/4 mile or less than 7 miles.
Peak Gust = Maximum 5-second average.
Snowfall data not observed at ASOS stations.

Copyright ©2009 Western Regional Climate Center - Desert Research Institute - Reno, Nevada.