I have created a new plugin. I actually think it is an extremely useful one and hard to believe I haven´t done this earlier.
The plugin is called “Deviations” and what it does it, it shows you differences between a selected period and the corresponding long-term average.
The plugin includes several pages, one that shows you a summary of all data, and then detailed pages for the particular parameters.
Data is presented in sortable tables, interactive graphs and heatmaps. It is grouped by years, months and the individual days.
No need for any settings, just upload to your plugins folder, add a link to the menu and you are done.