The first step is to get the data from NOAA such as from here:
http://www.crh.noaa.gov/sgf/climate/vih/vihf6.shtml

Or here (for Tulsa):
http://www.srh.noaa.gov/tulsa/cgi-bin/get_f6.pl?stn_name=Tulsa+International+Airport&month=Jan&a mp;year=2004

The NOAA website isn't orgainized very well so you have to hunt around to find the climate data for your area.

In the end NOAA gives tables of data in text by month and the raw data looks like this:

PRELIMINARY LOCAL CLIMATOLOGICAL DATA (WS FORM: F-6)

                                          STATION:   VICHY-ROLLA
                                          MONTH:     JANUARY
                                          YEAR:      2003
                                          LATITUDE:   38  7 N                  
                                          LONGITUDE:  91 46 W                  

  TEMPERATURE IN F:       :PCPN:    SNOW:  WIND      :SUNSHINE: SKY     :PK WND
===========================
1   2   3   4   5  6A  6B    7    8   9   10  11  12  13   14  15   16   17  18
                                          AVG MX 2MIN
DY MAX MIN AVG DEP HDD CDD  WTR  SNW DPTH SPD SPD DIR MIN PSBL S-S WX    SPD DR
===========================

 1  36  26  31   1  34   0 0.23    M    M  9.4 17  70   M    M   9 168    21  40
 2  30  26  28  -2  37   0 0.02    M    M  0.0  0 320   M    M  10 1       0 310
 3  33  17  25  -5  40   0 0.00    M    M  3.4 10 280   M    M   1 1      12 280
 4  46  26  36   6  29   0 0.15    M    M 10.3 17 310   M    M   2        21 310
 5  40  30  35   5  30   0 0.00    M    M  9.2 17 300   M    M   7 1      22 270
 6  39  20  30   0  35   0 0.00    M    M  8.1 16  20   M    M   6 18     21  20
 7  46  20  33   3  32   0 0.00    M    M 13.2 18 260   M    M   1 18     22 230
 8  68  40  54  25  11   0 0.00    M    M 15.2 25 250   M    M   0        30 260
 9  50  29  40  11  25   0 0.00    M    M 11.1 23 320   M    M   0        29 330

10.  32  20  26  -3  39   0 0.00    M    M 11.7 22 320   M    M   2        28 290
11.  30  14  22  -7  43   0 0.00    M    M  6.6 14 330   M    M   0        16 340

This is the raw data for the first eleven days of January 2003 for the airport in Vichy Missouri which is close to my site.

This gets pasted into a spreadsheet.  Most spreadsheets will automatically take the data in a one vertical column of text with the days of the month extending down in rows.  That's what you want if you're given formatting choices by the spreadsheet.

What I did is get the data for every month of one year and pasted them below each other in Excel until I had one year of data running vertically down my spreadsheet..  I know it sounds tedious but this is to develop baseline data for a location and you only have to do this once.

Now, how do get useful data from all this text?

The answer is string functions.

Remember the data you've pasted into your spreadsheet is text, not numbers.  It might as well be newspaper headlines as far as the spreadsheet is concerned.

Functions are little directives you put in a cell of a spreadsheet instead of data to tell it what you want in the cell.  The simplest function is a math function like =B1+C1.  In this case the cell that has this formula typed into it will hold the sum of whatever numbers are in cells B1 and C1.

In our case we use a string function.  Locate the cell that's holding all the text for the first day of the first month of your data.  In my case, from above its this one -

1  36  26  31   1  34   0 0.23    M    M  9.4 17  70   M    M   9 168    21  40

and the data above happened to be located at cell A10 in my spreadsheet

Now go to the right to an empty cell in the same row (like B10) and type =MID(A10,50,5) where A10 will need to be replaced with the location of your data cell.  What this function does is say that this cell is equal to the text located at the 50th character position and extending for 5 characters in the cell A10.  MID means text from somewhere in the middle of another string of characters.  Note this is still text, not a number.  B10 should now hold "70" which happens to be where the wind direction data is in the text from NOAA

Now go one more cell to the right of this one (C10) and type =VALUE(B10) assuming B10 is where you put the MID function.  Now the cell C10 actually holds a number rather than text.

Use the "fill down" feature to copy your formulas all the way to the bottom of your data.  Congratulations!  You now have a year long column of numerical data with the windspeed direction for your area.

Doing the same thing for wind speed, temperature, etc. is simply a matter of adding more columns with different values in the MID function.  For instance =MID(A10,5,4) grabs the text for the maximum temperature for that day.  You then use the Value function to convert this into a numeric value.

That's enough for tonight.  Next time: using trigonometry functions to make cool circular charts!

BTW:  I plan to add the trig part of the explanation on how to build the second chart but I probably won't get back to it for a few days.