STATION:  SEATTLE-BOEING FLD/KING CO INTL AP (KBFI), WA

CLIMATOLOGICAL SUMMARY.  Period of Record: Dec 1998 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        |  47.8  50.3  53.5  58.6  64.7  70.3  76.1  75.8  69.8  60.0  51.9  47.0 |   60.5
Avg Min Temp        |  36.8  36.3  39.8  42.6  48.3  53.5  57.5  57.5  52.7  46.2  39.7  36.4 |   45.6
Avg Temperature     |  42.3  43.3  46.6  50.6  56.5  61.9  66.8  66.6  61.2  53.1  45.8  41.7 |   53.0
                    |                                                                         |
Extremes:           |                                                                         |
    Extreme Max Temp|    63    64    79    82    89    93    95    91    87    78    64    61 |     95
                    |                                                                         |
    Date of Ext-Day |    07    24    29    16    26    07    23    13    14    06    08    14 |
               -Year|  2002  2005  2004  1999  2005  2003  2004  2002  2000  2000  2008  2002 |
                    |                                                                         |
    Extreme Min Temp|    17    20    27    30    32    44    49    49    40    29    19    15 |     15
                    |                                                                         |
    Date of Ext-Day |    12    18    03    03    14    04    02    31    28    31    29    22 |
               -Year|  2007  2006  2001  2008  1999  2001  1999  1999  1999  2002  2006  1998 |
                    |                                                                         |
Heating Degree Days |   703   613   570   432   270   127    32    26   129   369   576   722 |   4568
Cooling Degree Days |     0     0     0     0     6    34    87    76    15     0     0     0 |    218
                    |                                                                         |
Avg Number of Days: |                                                                         |
    Max Temp >= 90  |   0.0   0.0   0.0   0.0   0.0   0.5   1.1   0.3   0.0   0.0   0.0   0.0 |    1.9
    Max Temp >= 75  |   0.0   0.0   0.1   0.8   3.0   8.0  17.6  18.3   7.0   0.3   0.0   0.0 |   55.1
    Max Temp <= 32  |   0.3   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.1   0.9 |    1.3
                    |                                                                         |
    Min Temp <= 32  |   6.5   7.4   2.5   0.4   0.4   0.0   0.0   0.0   0.0   0.5   4.7   7.7 |   30.2
    Min Temp <= 20  |   0.5   0.1   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.1   0.7 |    1.4
    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  |  37.1  35.8  38.3  40.1  45.0  48.9  52.2  53.2  50.5  45.9  40.3  36.8 |   43.7
Avg Wet Bulb Temp   |  40.2  40.2  42.8  45.6  50.5  54.6  58.3  58.7  55.1  49.4  43.3  39.7 |   48.2
                    |                                                                         |
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                    |                                                                         |
Avg Sea Level Pres  | 30.11 30.12 30.09 30.05 30.06 30.04 30.04 30.02 30.03 30.10 30.12 30.13 |  30.08
(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   |   2.1   2.5   1.5   1.2   0.4   2.0   2.7   2.8   2.5   2.7   1.3   2.7 |   24.4
    Heavy Fog       |   2.2   1.3   0.5   0.2   0.2   0.0   0.0   0.1   0.2   2.3   2.8   3.3 |   13.1
    Fog             |  21.1  15.5  14.1  10.8   8.4   7.8   4.1   5.4   8.1  14.8  18.2  19.6 |  147.9
    Hail            |   0.2   0.1   0.7   0.0   0.0   0.1   0.2   0.0   0.0   0.0   0.1   0.3 |    1.7
                    |                                                                         |
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                    |                                                                         |
PRECIPITATION (In)  |   Jan   Feb   Mar   Apr   May   Jun   Jul   Aug   Sep   Oct   Nov   Dec |   Year
                    |                                                                         |
Average Monthly     |  5.94  3.35  3.53  2.12  1.90  1.35  0.56  1.08  1.19  2.87  6.23  5.92 |  36.04
                    |                                                                         |
Maximum Daily       |  1.97  1.19  1.42  1.05  1.11  1.27  0.66  1.58  1.06  4.04  2.14  3.96 |   4.04
                    |                                                                         |
    Date of Ext-Day |    17    01    26    13    31    11    16    22    30    20    06    03 |
               -Year|  2005  2000  2005  2002  2005  2001  1999  2001  2007  2003  2006  2007 |
                    |                                                                         |
Avg Number of Days: |                                                                         |
    >= 0.01         |  20.2  14.7  18.0  14.1  12.3   9.8   4.2   5.3   8.0  13.8  17.6  19.3 |  157.3
    >= 0.10         |  13.8   8.4  10.3   7.1   5.6   4.1   1.7   2.5   3.7   6.8  11.9  12.7 |   88.6
    >= 0.25         |   7.3   4.7   5.4   2.8   2.5   1.2   0.8   1.6   1.7   3.9   7.9   8.2 |   48.0
    >= 0.50         |   4.0   2.2   1.5   0.5   0.9   0.6   0.2   0.5   0.4   1.0   4.7   3.6 |   20.1
    >= 1.00         |   1.0   0.3   0.2   0.1   0.1   0.1   0.0   0.1   0.1   0.1   1.7   0.8 |    4.6
                    |                                                                         |
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                    |                                                                         |
WIND (MPH)          |   Jan   Feb   Mar   Apr   May   Jun   Jul   Aug   Sep   Oct   Nov   Dec |   Year
                    |                                                                         |
Daily Avg Wind Speed|   6.1   5.6   6.7   6.1   5.7   5.7   5.3   5.0   4.5   5.1   5.4   6.0 |    5.6
Daily Avg Max 2-Min |  15.3  14.7  16.4  14.6  13.8  13.5  12.6  12.5  12.4  13.6  14.1  15.5 |   14.1
Daily Avg Peak Gust |  20.8  20.0  22.3  20.0  19.1  18.7  17.8  17.5  17.3  19.0  19.6  21.6 |   19.5
                    |                                                                         |
Maximum Daily Avg   |  16.2  17.7  19.8  15.1  12.8  12.0  11.5  12.3  11.7  15.0  15.2  16.6 |   19.8
                    |                                                                         |
Maximum 2-Minute Avg|    36    36    59    28    25    23    22    21    24    29    31    39 |     59
                    |                                                                         |
Date of Max 2min-Day|    16    04    13    15    05    12    28    31    24    18    21    14 |
               -Year|  2000  2006  2000  2006  2002  2000  2001  2000  1999  2007  2006  2006 |
                    |                                                                         |
Maximum Peak Gust   |    51    47    59    39    32    39    32    31    37    41    43    56 |     59
                    |                                                                         |
Date of Max Gust-Day|    16    04    13    03    19    09    12    25    24    18    20    15 |
               -Year|  2000  2006  2000  2003  2000  2008  2006  2004  1999  2007  2001  2006 |
                    |                                                                         |
Avg Number of Days: |                                                                         |
   Peak Gust >=30   |   4.2   3.3   5.0   0.8   0.7   0.2   0.1   0.1   0.5   2.1   2.9   5.6 |   25.6
   Peak Gust >=40   |   0.6   0.3   0.6   0.0   0.0   0.0   0.0   0.0   0.0   0.2   0.2   1.1 |    3.1
   Peak Gust >=50   |   0.1   0.0   0.2   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.2 |    0.5
                    |                                                                         |
   Max 2-Minute >=30|   0.6   0.2   0.6   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.2   0.0 |    1.7
   Max 2-Minute >=40|   0.0   0.0   0.2   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0 |    0.2
                    |                                                                         |
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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.