27 years of accurate average weekly rainfall data for Lisbon, mapped out in 1.404 hand-cut wooden blocks, with 52 weeks per row
After some research and experimentations I ended up finding the historic daily precipitation data for Lisbon on a US government website (hah!).
The CSV data was imported into a MySQL table, over which I ran a script to visualize as best as possible how the bars would look. This script also allowed to highlight each group of bars and get their coordinates (year + week number). To simplify the process, each of the 1.404 bars was rounded to one of 16 groups.
Looking at the numbers it becomes noticeable that most weeks it didn’t rain at all (it’s Lisbon, after all) and then it quickly gets into smaller and smaller numbers of bars for weeks with more rainfall. Pictured is the script showing weeks with the rainfall “12 to 13” highlighted.
But before cutting the bars, the base panel (1,6cm thick MDF) had to be mapped out with a grid of 52 columns x 27 rows. Once that was done I used a saw mill to cut 21 stripes of 1,8cm x 1,8cm wood bars at a time, then sanding their imperfections individually.
Then the script showed me, group by group, the exact coordinates for each piece. The smaller ones were stapled into the base from the top (different staple lengths for different heights), the last ~40 taller ones had to be screwed into place from the back into the bar in the front.
A downside of using the stapler is that now each bar had an imperfection on the top, so I took plaster and individually covered the ~1.350 holes done by the staple, and then quickly sanded them all down.
After that it went straight to the painting and framing. Initially painted in blue, I ended up sanding it down again and painting in matte white for a much better interaction with light and resulting shadows. The frame was hand built to leave a gap between it and the base, and painted with a cherry wood tint and finished with a semi-gloss varnish.