We do not request rain except close to the rainy season.  R' Yehudah says: Of those [chazzanim] who stand before the Ark on the last Yom Tov of the festival —- the last [chazzan] mentions [the powers of rain, but] the first [chazzan] does not mention [it]. On the first Yom Tov of Pesach, the first [chazzan] mentions [the powers of rain, but] the last [chazzan] does not mention [it].  Until when do we request rain? R' Yehudah says: Until Pesach is over; R' Meir says: Until Nissan is over, as it is said: He caused rain to fall for you —- the early rain and the late rain —- in the first month.

On the third [day] of MarCheshvan we request rain; Rabban Gamliel says: On its seventh [day], fifteen days after the festival, so that the last [pilgrim straggler] of Israel may reach the Euphrates River.

If the seventeenth [day] of MarCheshvan arrived but rain did not fall, the [distinguished] individuals would start fasting [a series of] three fasts: They may eat and drink after dark, and they are permitted to work, bathe, anoint [themselves with oil], wear shoes, and have marital relations.

If Rosh Chodesh Kislev arrived but rain did not fall, Beis Din decrees [a series of] three fasts upon the [entire] community. They may eat and drink after dark, and they are permitted to work, bathe, anoint [themselves with oil], wear shoes, and have marital relations.