Upper and lower limit in matplotlib contourf

When the data range in matplotlib contourf does not correspond to the range of colorbar, matplotlib automatically adjust the range, even when set_clim is set manually.

(In other words, I needed a fixed colorbar regardless of the data)

The solution is set "levels" as follows;

interval = np.linspace(2.5,4.5, num=32, endpoint=True)

img=plt.contourf(LON, LAT, DATA,

vmin=2.5,vmax=4.5,

cmap = "jet",

levels=interval,

transform=ccrs.PlateCarree())