Dear authors,

based on the assessment of two referees, it appears that your manuscript bears potential for triggering the interest of a wider audience within HESS. Both referees have risen certain points that call for what I would consider moderate to major revisions. Especially the second assessment contains some more substantial issues that need to be addressed (essentially related to temporal resolution of input data for the Penman-Monteith based calculations of ETo, estimation of certain input parameters from other variables, justification of the use of the Mann-Kendall test for trend analysis [with a specific focus on auto-correlation issues]). From your responses to the issues mentioned by the referees, I am certain that you will be able to rapidly submit a revised version of your manuscript that will then undergo a second round of reviews.

Many thanks for your interest in HESS.

With best wishes,

Laurent Pfister

Dear authors,
following specific comments made by one referee, there now remain only some minor edits that need to be made to your manuscript. Before final publication, you would have to focus on a few specific points:
- develop in the manuscript on the non-linearity of the PM equation
- improve the figure captions for figs. 7 and 8
I look forward to receiving your final edits to the paper.
With best wishes,
Laurent Pfister

Dear authors,
given the latest round of edits, I have the pleasure to accept your manuscript for publication in HESS. Prior to that, there is just a small technical correction (i.e. typo) that I would suggest in the conclusions:
'This study provides an outstanding example of how climate change and interactions between different meteorological variables drive an increase of the ETo in a subtropical North Atlantic Island.'
Best regards,
Laurent Pfister