In that case there are only two stations that I have complete data for. This leaves me with the question how accurate is my model going to be considering I am modelling an area of 5,660 km2 and will have 2 weather stations approximately only 60km apart?
At any rate I also managed to overcome the error; it wasn't due to the -99 values (which obviously still is a problem i have to overcome) but due to an apostrophe in one of the station names- see OBJECTID #27 in the previously attached .csv.
Do you however have any suggestions regarding my missing data? It seems a waste to cut 40 weather stations...