MATLAB: Heatmap from a matrix with scattered values

heatmapinterpolationscattered interpolation

Hi!
I have measured temperatures in differents locations on one floor of a building. I would like to make a heatmap out of these values, but since the values are scattered I need to fill in the blank spots to see the temperature between my measurement points. I don't know how to do this two-dimensionally. How do I do this in MatLAB?
It is a 25×25 matrix which I have attached (Excel). I am already using this code to get a heatmap from my matrix.
    A = [25X25 matrix]; %Matrix to draw
    colormap('hot');   % set colormap
    imagesc(A);        % draw image and scale colormap to values range
    colorbar;          % show color scale
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