A. If you have too much rain you may not appreciate what a blessing the rains are. But the Torah is emphasising both the water and the right time.
Nachmanides says that rain in its season clears and cleans the air and fills the fountains and rivers, which, in their turn, are essential for prosperity and good health.
If the land is properly irrigated the crops grow and there is food for human beings and animals to eat as well as water to drink, and life and health are improved.
Rain is therefore the first and most important earthly blessing.