When you check the temperature in the morning, the question you're asking is usually not "How many degrees is it", but "How do I need to dress today?" The temperature answers that question, but only if you know how 43 or 55 or 61 (etc) degrees feels like. Often, I don't. But I know if I was cold or hot yesterday and I know what I wore. I've always wanted a site that simply told me how much colder or warmer today will be than yesterday. This information is available on some websites, but you usually have to dig for it. Ideally, the interaction should be as easy as doineedanumbrella.com.

Yestertemp is a weekend project that hopes to achieve this. It looks at the forecast for the next 12 hours and compares it to the same 12 hours during the previous day.

I'm attempting to keep the interaction as simple as possible by trying to get the user's location automatically and keeping the 'forecast' to the time frame that matters in the most common use case—a user checking the temperature before they get ready for their day.

I got the idea to use Google maps as a background from the excellent maps blog 41Latitude. Since I'm retrieving coordinates and geocoding to do the weather look up automatically, I thought I could style a map to signal to the user that the data is targeted to their location, and, quite frankly to avoid having to create my own graphics while providing something visually interesting.

Lastly, I can only retrieve data for the US and even some areas in the US don't have data available. Sorry. Please let me know if you run into any bugs.

This project was going to be called Deltabrrk, but I got talked out of it.

• last modified: 02/04/2011