My question is; should i be logging that data on a SD card on the actual weather station, and then only have the weather station send the requested data for the specified time period to the server when i log into my web page.
or should i have the weather station automatically periodicaly (say every 15min) send the updated logged data to the server (say my PC) so that the data is actually stored onto my PC and then have my web page request the data from my PC for the specified or period?
A mixed approach might work. Store the data on the SD card and push it to the server periodically. The server can do the heavy lifting on the data presentation, but you keep the data saved on the SD card until you get the chance to send it. This way, if the server's down for any reason, you won't lose any of your data.