We have just released an update to HadEX3 (version 3.0.2). It was brought to our attention that the land-sea mask used had an offset against the actual land sea boundary, something that was not spotted on the global-scale maps but was clear on regional cut-outs.
The net effect of this error was that grid boxes on the south/west were more likely to be categorised as sea rather than land, with the opposite for those on northern/eastern coasts. No grid box values or locations away from the coasts have changed. As an example, we show the trend maps for version 3.0.1 and 3.0.2 below (the Pacific coast of South America shows the change clearly).
HadEX 3.0.2 (TNn trend, 1950-2018) 
HadEX 3.0.1 (TNn trend, 1950-2018)
This has been corrected for all indices and reference periods and as of 5th November, the new netCDF and image files are available online at Hadobs and Climdex. No other changes were made to the input data, and so there are only very minor changes to grid boxes on coastlines.
