Whilst the basic notion that travel sites could do a better job at giving you suggestions based on your preferences - and temperature definitely being one factor - temperature is not everything.
The author did a nice job collecting all the temperature information, but for an end user the simple names of the destinations don't mean much (where exactly is "Metehara" without asking Google?). I wouldn't find myself just looking for a temperature and in accordance to that look for destinations. Much more important for a holiday is the price range, so if I'd use the Excel file to find my perfect destination I would still have to find all the prices associated with the destinations (e.g. traveling to Ethiopia / Metehara will be quite expensive).
All in all: Good start. Incorporate this data within a larger travel search engine and let the user have one more option to narrow down the search.