Contourf opacity level when plotted on the map

[imlaguiar]

I was able to plot 2D array data on the map with the contourf method from matplotlib, although, the opacity level is too low even if I set alpha to the maximum value. I'd like to know if there is any specific reason for that to happen.
This is how it looks on the library map:

And this how it looks on a regular basemap instance:

My guess is that the library on its own decrease the opacity so it can show the map details under the filled contour when it is opened, if so, how could I bypass this? I need the max opacity level.