Not quite. It actually rains mainly NOT in the plain. Castille is, in superficial appearance, a barren land scarcely blessed by rain, difficult to culture and to live from. But, at the same time, the region is the main wheat supplier for the rest of Spain. And its scenery of distant horizons with a few poplars signaling water spots, with no sign of the hordes of tourists stuffing coastal resorts, is the epitomy of peace and pristine air, close to what one experiences in the great deserts and plains of the world.
With a difference: Castille is not quite as barren as it may appear.