I used the National Weather Service --https://www.weather.gov/-- for mine. Click on Past Weather, pick your area, then set the parameters. You can get an entire month in one chart.

This is the temperature quilt I made for my sister for her 80th -- temps on her birthday each year.

Dunster, I, too, did not see the appeal for 365 days of temperatures. I chose my birth day history to have a personal meaning to me. Plus, I enjoyed practicing FMQ on the new sit-down machine.
I did like the blog idea of separating the months into houses!

@stitch678 Wow! I love that house treatment. I've chosen the first year in our new house and was planning on some bars of seasons (like the trees). That is making me rethink things... and here I was so firm in my idea when I first posted!

@dunster The appeal is difficult to explain. One way is that it can commemorate a year or date. I like secret messages in my quilts, have used morse and other codes to do so... so "hiding" in plain sight appeals to me. Lastly, is it tickles my mathematical mind and interest in statistics and randomness... I like designing in a structure that has outside forces making me do something, and still trying to get something artistic out of it!

Those are some neat patterns and pretty quilts you've all shared.

I made my temperature quilt in 2022 and was able to find the readings for a weather station just a few houses away from mine, so the temperatures were very accurate for my location. The pattern I chose was inspired by Corey Yoder's "Playful Petals" quilt book. I'm sorry I can't help with advice on finding information for past years.

To answer Dunster's question, personally the appeal for me was the fun of mixing academics with creativity. Some years back, I made a bar graph quilt by using Pi as the pattern. Also, inspired by a piece on display at the Smithsonian Air & Space Museum, called "The Electromagnetic Spectrum in Stained Glass", which was the artist's depiction of various light rays that penetrate Earth's atmosphere, I've mulled over coming up with a quilt design on similar lines. I just really enjoy that kind of thing.

Here are pictures of both my temperature quilt and my Pi quilt (if that's alright to include it here).