STATION:  RIVERTON REGIONAL AIRPORT (KRIW), WY

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        |  31.6  36.7  48.0  56.9  67.9  78.3  89.4  85.3  72.5  57.9  42.7  31.1 |   58.2
Avg Min Temp        |  10.3  14.3  22.9  31.0  40.5  48.8  57.9  55.0  44.7  33.0  20.0  10.0 |   32.4
Avg Temperature     |  21.0  25.5  35.5  44.0  54.2  63.6  73.6  70.2  58.6  45.4  31.4  20.6 |   45.3
                    |                                                                         |
Extremes:           |                                                                         |
    Extreme Max Temp|    63    62    74    84    93    98   102    99    93    84    69    59 |    102
                    |                                                                         |
    Date of Ext-Day |    01    23    31    29    29    29    13    06    16    01    04    11 |
               -Year|  1997  2002  2004  2007  2003  2002  2005  2001  2000  2005  1999  2004 |
                    |                                                                         |
    Extreme Min Temp|   -25   -25    -7     4    19    32    42    40    21     2   -11   -21 |    -25
                    |                                                                         |
    Date of Ext-Day |    22    17    08    11    09    03    01    31    27    30    12    20 |
               -Year|  2008  2006  1998  1997  2002  1998  1999  2005  1996  2002  2000  1998 |
                    |                                                                         |
Heating Degree Days |  1365  1116   916   631   345   116     5    19   224   607  1008  1377 |   7729
Cooling Degree Days |     0     0     0     0    10    73   273   178    32     0     0     0 |    566
                    |                                                                         |
Avg Number of Days: |                                                                         |
    Max Temp >= 90  |   0.0   0.0   0.0   0.0   0.3   4.0  16.4   9.2   1.3   0.0   0.0   0.0 |   31.1
    Max Temp >= 75  |   0.0   0.0   0.0   1.3   9.9  20.0  30.0  28.5  14.8   2.2   0.0   0.0 |  106.6
    Max Temp <= 32  |  15.6   9.1   3.9   1.0   0.0   0.0   0.0   0.0   0.2   0.9   6.6  16.7 |   54.0
                    |                                                                         |
    Min Temp <= 32  |  30.7  27.9  27.7  17.2   4.4   0.2   0.0   0.0   1.8  14.5  27.8  30.7 |  182.9
    Min Temp <= 20  |  25.5  19.7  10.3   2.8   0.1   0.0   0.0   0.0   0.0   1.9  12.8  25.9 |   99.0
    Min Temp  <= 0  |   5.3   3.0   0.6   0.0   0.0   0.0   0.0   0.0   0.0   0.0   1.5   6.0 |   16.5
                    |                                                                         |
Avg Dew Point Temp  |  11.4  13.6  18.0  23.2  31.4  36.7  40.7  40.1  34.5  27.3  18.5  11.3 |   25.6
Avg Wet Bulb Temp   |  18.0  21.3  28.7  35.1  43.2  49.6  55.3  53.8  46.4  37.2  26.5  17.7 |   36.1
                    |                                                                         |
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                    |                                                                         |
Avg Sea Level Pres  | 30.14 30.10 30.05 30.05 29.96 29.93 29.91 29.93 29.98 30.06 30.14 30.16 |  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   |   0.0   0.1   0.0   0.2   0.3   0.5   0.6   0.5   0.2   0.0   0.0   0.0 |    2.4
    Heavy Fog       |   4.3   2.9   2.2   2.2   0.7   0.1   0.2   0.2   0.5   1.4   3.2   2.6 |   20.4
    Fog             |   9.0  10.1   6.8   6.2   4.0   3.1   1.1   1.8   4.0   4.4   7.1   7.5 |   65.0
    Hail            |   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
                    |                                                                         |
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                    |                                                                         |
PRECIPITATION (In)  |   Jan   Feb   Mar   Apr   May   Jun   Jul   Aug   Sep   Oct   Nov   Dec |   Year
                    |                                                                         |
Average Monthly     |  0.14  0.29  0.38  1.02  1.44  0.97  0.57  0.55  0.62  0.77  0.21  0.18 |   7.15
                    |                                                                         |
Maximum Daily       |  0.22  0.46  0.98  0.72  2.00  0.94  0.71  0.65  0.44  1.00  0.37  0.29 |   2.00
                    |                                                                         |
    Date of Ext-Day |    04    28    28    09    26    24    28    18    17    04    06    07 |
               -Year|  2005  2004  2006  2004  2008  2003  1997  2004  2002  1998  1998  2007 |
                    |                                                                         |
Avg Number of Days: |                                                                         |
    >= 0.01         |   2.9   4.8   4.5   6.1   8.1   6.2   3.9   5.4   6.5   5.6   3.4   3.5 |   60.8
    >= 0.10         |   0.4   0.8   1.5   3.2   3.2   2.7   1.6   1.8   2.0   2.0   0.8   0.5 |   20.7
    >= 0.25         |   0.0   0.2   0.1   1.7   1.8   1.2   0.9   0.5   0.9   0.8   0.1   0.2 |    8.3
    >= 0.50         |   0.0   0.0   0.1   0.5   0.7   0.5   0.2   0.2   0.0   0.4   0.0   0.0 |    2.5
    >= 1.00         |   0.0   0.0   0.0   0.0   0.3   0.0   0.0   0.0   0.0   0.1   0.0   0.0 |    0.3
                    |                                                                         |
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                    |                                                                         |
WIND (MPH)          |   Jan   Feb   Mar   Apr   May   Jun   Jul   Aug   Sep   Oct   Nov   Dec |   Year
                    |                                                                         |
Daily Avg Wind Speed|   7.2   7.6   9.2   9.7   9.5   9.4   9.0   8.6   8.3   8.1   7.2   7.0 |    8.4
Daily Avg Max 2-Min |  19.0  19.3  22.8  23.5  24.7  25.4  24.1  23.6  21.1  20.2  18.5  18.3 |   21.7
Daily Avg Peak Gust |  22.3  22.8  27.4  28.9  30.2  31.3  29.9  28.9  25.5  24.2  21.8  21.6 |   26.2
                    |                                                                         |
Maximum Daily Avg   |  31.1  24.8  24.2  26.8  22.4  18.9  20.6  18.6  20.4  26.7  21.7  24.5 |   31.1
                    |                                                                         |
Maximum 2-Minute Avg|    53    52    47    46    53    49    46    48    53    48    40    46 |     53
                    |                                                                         |
Date of Max 2min-Day|    07    14    16    16    22    16    31    25    12    25    07    20 |
               -Year|  2007  2000  1999  2006  2006  1999  1998  2006  2005  2008  1996  2004 |
                    |                                                                         |
Maximum Peak Gust   |    71    66    59    62    74    64    54    59    62    60    51    59 |     74
                    |                                                                         |
Date of Max Gust-Day|    07    16    28    20    20    30    31    30    15    25    21    05 |
               -Year|  2007  2007  2007  2008  2008  2008  1998  1998  2006  2008  2008  2005 |
                    |                                                                         |
Avg Number of Days: |                                                                         |
   Peak Gust >=30   |   8.4   7.7  13.1  13.3  16.5  16.3  15.8  13.4   9.5   8.3   7.2   7.7 |  137.0
   Peak Gust >=40   |   3.5   3.0   5.2   4.1   3.9   5.2   3.7   5.0   2.9   2.8   2.2   3.0 |   44.4
   Peak Gust >=50   |   0.5   0.5   0.7   1.0   0.9   0.9   0.5   1.1   0.6   0.5   0.1   0.6 |    7.9
                    |                                                                         |
   Max 2-Minute >=30|   5.4   4.4   8.0   6.6   7.5   8.7   6.8   7.2   4.9   4.3   3.9   0.0 |   67.7
   Max 2-Minute >=40|   0.8   0.8   1.2   1.2   1.0   1.4   0.7   1.1   0.8   0.8   0.2   0.0 |   10.0
                    |                                                                         |
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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.