Easy there, Chief! What you should be doing is occasionally clicking on the "New Features!" link on the very top right of your Google Calendar pages, where it explains how to do just that.

But I'll walk you through it too, so you can get Instant. Gratification. :-)

Log in to your Google Calendar account, then click on the "Settings" link immediately adjacent to "New Features":

Now you have a huge, rather overwhelming number of options presented to you, but what you need to do is find the location and weather options:

Specify where you live (or the location for which you want weather forecasts) and choose to either have the temperature shown in celsius or fahrenheit, then remember to select "Save" at the bottom. That's all there is to it!

Now when you look at your daily, weekly or monthly view, today and the few days following have little weather icons and if you move your cursor over one of 'em, you'll get a micro weather forecast:

Hope that helps you keep up with your buddies!

p.s.: one advantage to watching the "new features" link is that you can often learn about things before Google even really publicizes them! I wrote this article three days prior to Google finally blogging about weather on its site. :-)