STATION: NAPA COUNTY AIRPORT (KAPC), CA
CLIMATOLOGICAL SUMMARY. Period of Record: May 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
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Avg Max Temp | 55.4 59.7 64.4 66.7 73.2 78.1 78.9 79.7 79.4 74.0 63.9 56.5 | 69.1
Avg Min Temp | 36.8 38.3 39.8 41.1 46.1 50.4 53.4 52.6 49.4 43.8 39.7 36.3 | 44.0
Avg Temperature | 46.1 49.0 52.1 53.9 59.7 64.2 66.1 66.2 64.4 58.9 51.8 46.4 | 56.6
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Extremes: | |
Extreme Max Temp| 68 77 85 91 101 110 106 101 102 95 84 78 | 110
| |
Date of Ext-Day | 21 16 10 26 15 14 22 03 21 12 15 19 |
-Year| 2007 2007 2004 2004 2008 2000 2006 1998 2003 2001 2005 1999 |
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Extreme Min Temp| 18 23 28 25 33 36 43 42 37 30 22 19 | 18
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Date of Ext-Day | 15 08 08 24 09 08 01 31 25 31 12 22 |
-Year| 2007 2003 2002 2008 2003 1999 2007 2008 2005 2002 2000 1998 |
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Heating Degree Days | 586 452 401 334 181 69 30 26 69 195 397 575 | 3315
Cooling Degree Days | 0 0 1 1 16 46 65 61 51 6 0 0 | 247
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Avg Number of Days: | |
Max Temp >= 90 | 0.0 0.0 0.0 0.2 1.4 3.1 2.5 2.9 4.8 0.7 0.0 0.0 | 15.5
Max Temp >= 75 | 0.0 0.2 3.2 4.4 11.0 18.5 22.0 23.2 19.8 13.4 2.2 0.1 | 118.0
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
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Min Temp <= 32 | 9.6 5.1 2.4 1.9 0.0 0.0 0.0 0.0 0.0 0.1 4.7 11.5 | 35.2
Min Temp <= 20 | 0.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.3 | 0.5
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
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Avg Dew Point Temp | 40.7 42.5 44.1 44.8 48.8 51.3 54.4 54.3 50.8 45.2 44.2 40.4 | 46.8
Avg Wet Bulb Temp | 43.7 46.0 48.1 49.3 53.5 56.6 58.6 58.5 56.1 50.9 48.1 43.6 | 51.1
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Avg Sea Level Pres | 30.13 30.06 30.04 30.00 29.95 29.90 29.91 29.90 29.88 29.97 30.08 30.13 | 30.00
(Inches of Mercury) | |
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WEATHER | Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec | Year
See disclaimer below| |
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Avg Number of Days: | |
Thunderstorms | 0.4 0.5 0.4 0.2 0.4 1.0 0.5 0.3 0.5 0.7 0.5 0.4 | 5.7
Heavy Fog | 7.4 4.0 4.3 2.1 1.6 0.6 0.5 1.5 2.6 4.0 6.5 5.5 | 40.5
Fog | 22.2 18.2 18.1 12.6 12.0 6.9 9.8 11.5 13.1 14.7 19.7 19.1 | 177.9
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
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Average Monthly | 3.27 4.02 1.86 1.12 0.71 0.08 0.00 0.03 0.06 0.72 2.18 4.39 | 18.43
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Maximum Daily | 2.10 2.13 1.17 1.04 0.81 0.37 0.01 0.30 0.30 0.91 1.90 2.44 | 2.44
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Date of Ext-Day | 04 27 05 11 08 08 20 21 24 26 01 13 |
-Year| 2008 2006 2006 1999 2005 2005 2005 2003 2001 2004 2008 2002 |
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Avg Number of Days: | |
>= 0.01 | 12.6 12.3 10.3 6.8 4.1 0.9 0.3 0.5 2.0 4.5 11.1 12.5 | 77.9
>= 0.10 | 7.3 7.6 5.0 3.6 1.7 0.2 0.0 0.1 0.1 1.9 4.1 7.5 | 39.1
>= 0.25 | 4.3 4.8 2.6 1.5 1.3 0.1 0.0 0.1 0.1 0.9 2.8 5.0 | 23.5
>= 0.50 | 2.1 2.6 1.0 0.4 0.6 0.0 0.0 0.0 0.0 0.5 1.5 2.8 | 11.6
>= 1.00 | 0.5 1.1 0.1 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.5 1.3 | 3.5
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WIND (MPH) | Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec | Year
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Daily Avg Wind Speed| 6.8 6.5 7.1 8.5 9.1 9.9 9.9 9.1 7.4 6.0 5.5 6.6 | 7.7
Daily Avg Max 2-Min | 16.9 16.9 18.2 20.5 19.9 20.2 19.2 18.5 17.0 15.9 15.2 16.9 | 17.9
Daily Avg Peak Gust | 20.1 20.0 21.4 24.4 23.5 23.4 22.3 21.6 19.8 18.7 18.2 20.4 | 21.2
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Maximum Daily Avg | 18.2 19.2 18.0 17.3 20.2 17.9 15.9 15.5 14.3 20.4 16.4 18.0 | 20.4
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Maximum 2-Minute Avg| 39 41 41 38 32 38 29 32 31 34 41 37 | 41
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Date of Max 2min-Day| 04 28 01 08 02 05 26 12 17 21 24 16 |
-Year| 2008 2002 2002 2005 2001 2007 2000 2008 2004 2000 2001 2002 |
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Maximum Peak Gust | 52 49 48 46 39 44 33 61 38 43 59 51 | 61
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Date of Max Gust-Day| 04 28 01 08 02 05 26 12 22 21 08 16 |
-Year| 2008 2002 2002 2005 2001 2007 2000 2008 2006 2000 2008 2002 |
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Avg Number of Days: | |
Peak Gust >=30 | 3.0 3.9 3.8 5.9 4.8 2.8 2.3 1.4 1.0 1.6 2.1 3.8 | 36.4
Peak Gust >=40 | 0.3 0.6 0.1 0.7 0.0 0.1 0.0 0.1 0.0 0.2 0.3 0.5 | 2.8
Peak Gust >=50 | 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.0 0.0 0.2 0.1 | 0.5
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Max 2-Minute >=30| 1.1 0.9 1.0 1.5 0.8 0.3 0.0 0.2 0.2 0.3 0.6 0.0 | 6.8
Max 2-Minute >=40| 0.0 0.1 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.0 | 0.3
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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.