The surf function expects a matrix, so you will have to convert your linear data to a matrix. The accumarray function is a very flexible tool and worth exploring if you've never seen it before. A general advice would be to read the documentation for functions you are trying to use, and read the related functions linked at the bottom if you think it doesn't quite do what you need.
The code below should result in a plot you expect. Play around with the syntax for surf and colorbar to get the exact output you want.
filename='Temperature.csv';
Data = csvread(filename,6,0);
X_data=Data(:,1);
Y_data=Data(:,2);
T_data=Data(:,4);
[x,~,xi]=unique(X_data);
[y,~,yi]=unique(Y_data);
subs=[xi yi];
val=T_data;
M=accumarray(subs,val,[],[],NaN);
[X,Y]=ndgrid(x,y);
figure(1),clf(1)
surf(X,Y,M)
view(0,90),xlabel('x'),ylabel('y')
colorbar
