import matplotlib.pyplot as plt
import numpy as np

# Make fake data

d = np.random.rand(11,18)
azimuths = np.radians(np.arange(-42.5,42.6,5))
radials = np.linspace(1.3,3.9,11)
r, theta = np.meshgrid(radials, azimuths)

# Plot the data

fig = plt.figure(figsize=(6,6))

ax1 = fig.add_subplot(111,polar=True)

cont = ax1.contourf(theta, r, np.fliplr(d).T,
                   )

ax1.set_theta_zero_location('N')
ax1.set_thetamin(-45)
ax1.set_thetamax(45)
ax1.set_xticks(np.arange(np.radians(-45),
                        np.radians(46),
                        np.radians(15),
                       ))  # Less radial ticks


ax1.set_xticklabels(np.arange(-45,46,15)[::-1],
                    fontsize='xx-large',            # This argument controls azimuthal tick labels
                   )

ax1.set_yticklabels(np.arange(-45,46,15)[::-1],
                    fontsize='xx-large',            # So why does this not control the radial tick labels?
                   )

# ax1.yaxis.set_tick_params(labelsize='xx-large')      # Especially when this line *does* control them

plt.show()