I would think there are 2 different approaches to adding ads.
1. Google ads - This is probably the easiest. Most of the ads would probably not be for the local businesses.
2. Local businesses Sponsor - This would take some sales skills. Put yourself in their shoes. If you were a local business, what would you hope to gain from advertising on a weather website?
Have you used Google Analytics http://www.google.com/intl/en/analytics/index.html
to study the people who are visiting? I have averages about 32,000 hits per year over 3 years. But that is not really important. Probably 10% of those hits are me.
What is important is unique visitors. I get roughly 50 unique visitors a day. Of those I am guessing 30% are not from around here. (visiting from forums, or webcam hoping) So of the 35 people who are local, (meaning 7 county region) how many would actually respond to an ad? If a sponsor were to pay, say $50 per year to advertise, what would his Return On Investment (ROI) be?
Personally I hate ads and I am an avid user of ad blocking software. One picture ads are not so bad, but the internet is now filled with scrolling, popping, flashing, etc.. ads that are so obnoxious that it is hard to see the webpage. If I want to buy something, I just Google it to find the best deal.