Data Viz Done Right

June 22, 2015

Makeover Monday: Historical Rainfall in 3 of Australia's Largest Cities

A few weeks ago, the Guardian Datablog published this series of circular heatmaps to represent monthly rainfall across a 20 year period in three Australian cities.


There are several problems with using radial heatmaps:
  • They are not too dissimilar from geographical heatmaps in that they tend to skew towards the segments that cover the most surface area, in this case 2015.
  • It’s difficult to compare across years, across months, and across months and years.
  • Your eyes are drawn all over the place.
  • There’s very little sense for trends.
  • Like a pie chart, you’re trying to compare the angles of the slices, which is nearly impossible.
There are some other issues with this particular implementation:
  • The hover does not work once you get to the smaller segments.
  • The labels are quite hard to read.
  • When I hover, all I get is the value. This means that I have to look back to the labels to see which month and year it refers to.
Given these problems, I created this alternative version.
In this version, I have:
  1. Taken the radial heatmap and flattened it out. I liked their idea of using a heatmap, but needed it to be easier to read.
  2. Added two trend charts: (1) cumulative rainfall, (2) monthly rainfall
  3. Added a selector for the city
  4. Added a highlight action on the year
  5. Included informative tooltips
  6. Improved the title

You can download the viz from Tableau Public here. What would you do differently? What could be improved in my version?