import matplotlib.pyplot as mpl
import cartopy.crs as ccrs

fig = plt.figure()
ax = fig.add_subplot(projection=ccrs.LambertConformal(central_longitude=10, central_latitude=30))
ax.set_extent([-20,40,20,60])
ax.coastlines()
gl = ax.gridlines(xlocs=np.arange(-180,181,10), ylocs=np.arange(-90,91,10),
                  x_inline=False, y_inline=False,
                  **{'linewidth':0.5, 'color':'silver', 'linestyle':'--'})
gl.bottom_labels = True
gl.right_labels = True