Series argument in pygmt.makecpt

I am trying to understand what happens in my grid image when values in my gridded data exceed the series/range of the CPT.

I am defining my series in makecpt as [-1,1] since most of my gridded data falls within that range and I want to visually emphasize the variations within this range.
I know some of my data is outside of this range – what happens in the grid image at these points whose value don’t fall within the series range?

gridded_data = one_day.ugos
fig = pygmt.Figure()
pygmt.makecpt(cmap="roma", series=[-1,1])
             frame=["afg", "+tZonal absolute geostrophic velocity+s2021-01-31"])
fig.colorbar(frame=['af',"y+lVelocity (m/s)"])

I am new to PyGMT. Using version 0.9.0

Welcome to the forum! The default behavior uses the background and foreground colors of the original CPT for data outside the range included in pygmt.makecpt(). You can adjust this using the background, overrule_bg, or no_bg parameters.

Thank you!