Domestic cats are seasonal induced ovulators. In natural light, queens
will cycle from January to mid-October - but they can be induced to cycle
year-round with artificially increased daylength (14-16 hrs light daily).
The cycle itself works like this:

Proestrus - rarely observed in cats.
Estrus - 6-10 days, range 12 hrs to 19 days, +/- effect of breeding.
Clinical appearance of estrus: lordosis, vocalization, increased
affection, positive stimulation and allowing the male to mount.
Vaginal cytology in estrus: vaginal epithelial cells become cornified but
not to the same extent as canine vaginal cells.
Postestrus - 13-18 days. This is the period after an estrus in which the
queen was not induced to ovulate.
Diestrus - period after an estrus in which the queen was induced to
ovulate. The Corpus Luteum persists, and progesterone is produced. Length
if a fertile mating occurred (that is to say, gestation length) is 65-66
days with a range of 63 to 71. If nonfertile mating occurred,
pseudopregnancy will follow with a length of 40-50 days.

What's induced ovulation, anyway?
Induced ovulators include domestic cats, ferrets, rabbits, mink, skunks,
13-lined ground squirrels, camels, llamas, short-tailed shrews, possibly
tigers, possibly cheetahs, possibly jaguars, and my personal favorite, the
giant fruit bat. These animals require an external trigger, usually
coitus, to stimulate GnRH (gonadotropin releasing hormone) release and the
subsequent LH (luteinizing hormone) surge which induces ovulation. The
amount of LH released will be dependent on the timing and number of
copulations. 50% of queens bred only once showed progesterone levels
indicative of ovulation, while 100% of those mated at least 4 times
apparently ovulated. Some evidence does exist that cats can occasionally
spontaneously ovulate or ovulate secondary to a trigger other than coitus.