STATION:  BUTTE-BERT MOONEY AIRPORT (KBTM), MT

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        |  31.8  35.3  43.8  51.6  61.5  69.7  83.1  80.5  68.3  55.2  41.4  30.7 |   54.4
Avg Min Temp        |   8.0   9.6  18.9  26.0  33.9  41.0  46.5  43.7  35.6  26.7  16.5   7.5 |   26.2
Avg Temperature     |  19.9  22.4  31.4  38.8  47.7  55.3  64.8  62.1  52.0  41.0  28.9  19.1 |   40.3
                    |                                                                         |
Extremes:           |                                                                         |
    Extreme Max Temp|    57    57    68    76    88   100    98    99    93    79    70    53 |    100
                    |                                                                         |
    Date of Ext-Day |    23    03    30    29    28    30    30    03    04    22    12    10 |
               -Year|  2005  2005  2004  2007  2003  2000  2000  2000  1998  2003  1999  2004 |
                    |                                                                         |
    Extreme Min Temp|   -38   -37   -19    -1    17    28    31    27    17   -11   -19   -39 |    -39
                    |                                                                         |
    Date of Ext-Day |    12    24    02    03    09    05    05    31    23    31    05    21 |
               -Year|  1997  2003  2002  2001  2002  1998  1999  2006  1996  2002  2003  1998 |
                    |                                                                         |
Heating Degree Days |  1398  1203  1042   787   537   297    69   117   394   745  1083  1422 |   9093
Cooling Degree Days |     0     0     0     0     0     7    61    27     3     0     0     0 |     98
                    |                                                                         |
Avg Number of Days: |                                                                         |
    Max Temp >= 90  |   0.0   0.0   0.0   0.0   0.0   0.5   6.1   3.3   0.5   0.0   0.0   0.0 |   10.4
    Max Temp >= 75  |   0.0   0.0   0.0   0.2   4.3  10.5  27.5  24.8   9.3   0.8   0.0   0.0 |   77.4
    Max Temp <= 32  |  14.8   9.6   3.9   0.6   0.0   0.0   0.0   0.0   0.0   0.9   6.0  16.2 |   52.1
                    |                                                                         |
    Min Temp <= 32  |  30.3  28.2  29.8  25.4  12.9   2.9   0.1   0.5  10.1  23.7  28.3  30.4 |  222.7
    Min Temp <= 20  |  24.5  22.1  15.5   5.4   0.7   0.0   0.0   0.0   0.1   5.7  17.8  25.4 |  117.0
    Min Temp  <= 0  |   8.2   5.8   1.5   0.1   0.0   0.0   0.0   0.0   0.0   0.3   3.7   9.2 |   28.8
                    |                                                                         |
Avg Dew Point Temp  |  12.3  12.0  18.6  24.1  30.4  37.5  40.4  38.1  32.8  25.7  17.3  11.9 |   25.1
Avg Wet Bulb Temp   |  17.6  18.3  26.5  32.2  39.7  46.3  52.1  49.3  42.3  33.7  23.5  17.2 |   33.2
                    |                                                                         |
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                    |                                                                         |
Avg Sea Level Pres  | 30.20 30.15 30.07 30.03 30.00 29.96 29.97 29.99 30.02 30.11 30.19 30.20 |  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   |   0.0   0.0   0.0   0.5   3.8   7.9   8.4   6.7   1.8   0.4   0.0   0.1 |   29.4
    Heavy Fog       |   3.0   2.2   2.4   1.5   0.8   0.5   0.1   0.2   0.3   0.8   2.0   2.6 |   16.4
    Fog             |   9.2   8.0   7.8   8.5   5.2   3.6   1.2   1.9   2.8   4.4   7.8   8.7 |   69.0
    Hail            |   0.0   0.0   0.0   0.0   0.2   0.0   0.2   0.2   0.1   0.0   0.0   0.0 |    0.7
                    |                                                                         |
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                    |                                                                         |
PRECIPITATION (In)  |   Jan   Feb   Mar   Apr   May   Jun   Jul   Aug   Sep   Oct   Nov   Dec |   Year
                    |                                                                         |
Average Monthly     |  0.49  0.41  0.50  1.51  1.94  2.31  1.03  1.25  0.99  0.74  0.53  0.54 |  12.25
                    |                                                                         |
Maximum Daily       |  0.58  0.38  0.35  1.09  1.22  1.35  1.02  0.84  0.86  0.52  0.72  0.74 |   1.35
                    |                                                                         |
    Date of Ext-Day |    01    12    31    05    24    04    19    22    05    05    18    25 |
               -Year|  1997  2007  1997  2006  1997  2008  1997  2003  2007  2007  1996  1996 |
                    |                                                                         |
Avg Number of Days: |                                                                         |
    >= 0.01         |   7.0   6.8   7.5  11.0  11.7  13.9   8.2   8.2   6.8   7.5   7.2   7.2 |  103.1
    >= 0.10         |   1.9   1.5   1.7   4.7   5.8   6.2   3.6   3.8   2.6   2.6   1.6   1.5 |   37.6
    >= 0.25         |   0.2   0.2   0.3   2.3   2.8   2.8   1.2   1.5   1.5   0.8   0.3   0.4 |   14.2
    >= 0.50         |   0.1   0.0   0.0   0.5   0.6   1.2   0.2   0.8   0.5   0.1   0.1   0.2 |    4.2
    >= 1.00         |   0.0   0.0   0.0   0.1   0.1   0.2   0.1   0.0   0.0   0.0   0.0   0.0 |    0.4
                    |                                                                         |
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                    |                                                                         |
WIND (MPH)          |   Jan   Feb   Mar   Apr   May   Jun   Jul   Aug   Sep   Oct   Nov   Dec |   Year
                    |                                                                         |
Daily Avg Wind Speed|   4.3   4.4   6.3   6.5   6.8   6.4   6.0   5.8   5.3   5.5   4.5   4.3 |    5.5
Daily Avg Max 2-Min |  14.2  14.4  18.9  19.9  20.6  20.9  20.9  20.7  17.9  17.5  14.9  14.7 |   17.9
Daily Avg Peak Gust |  18.0  18.0  24.3  25.5  26.5  27.0  27.2  26.9  22.9  22.4  18.9  18.5 |   23.0
                    |                                                                         |
Maximum Daily Avg   |  13.8  16.1  13.8  18.0  14.0  15.4  12.5  12.2  12.7  16.1  13.8  16.0 |   18.0
                    |                                                                         |
Maximum 2-Minute Avg|    39    33    37    36    39    46    41    43    37    33    37    37 |     46
                    |                                                                         |
Date of Max 2min-Day|    30    16    25    13    02    27    16    19    09    27    27    13 |
               -Year|  2004  2007  2007  2004  2007  2002  2001  2008  2005  2003  2000  2008 |
                    |                                                                         |
Maximum Peak Gust   |    45    48    49    49    54    52    53    62    46    45    47    51 |     62
                    |                                                                         |
Date of Max Gust-Day|    30    07    11    13    20    27    14    29    09    29    13    29 |
               -Year|  2004  2008  2002  2004  2006  2002  2001  2006  2005  2003  2006  2008 |
                    |                                                                         |
Avg Number of Days: |                                                                         |
   Peak Gust >=30   |   3.6   3.5   8.4   7.4   9.5   9.6  11.5  10.2   6.2   5.2   4.4   3.8 |   83.3
   Peak Gust >=40   |   0.8   0.5   1.1   1.5   0.8   1.8   1.8   2.3   0.6   0.8   0.9   0.9 |   13.6
   Peak Gust >=50   |   0.0   0.0   0.0   0.0   0.1   0.1   0.5   0.9   0.0   0.0   0.0   0.1 |    1.7
                    |                                                                         |
   Max 2-Minute >=30|   0.6   0.8   1.4   1.9   1.4   2.6   2.5   3.0   0.9   0.9   0.7   0.0 |   16.6
   Max 2-Minute >=40|   0.0   0.0   0.0   0.0   0.0   0.1   0.3   0.3   0.0   0.0   0.0   0.0 |    0.6
                    |                                                                         |
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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.