Zmanim · The moments of the day
What is chatzot?
Chatzot (halachic midday) is the exact midpoint between sunrise and sunset — solar noon, not 12:00 on the clock. It marks the end of the time for the morning prayer and the opening of the time for Minchah, the afternoon prayer.
Noon that the sun decides
Chatzot — חצות — is midday, but not the midday of the clock on the wall. It is the true center of the daylight, the moment exactly halfway between sunrise and sunset, when the sun stands at its highest. On the clock it may fall well before or after twelve, depending on your longitude and the season. It quietly divides the day: the morning behind it, the afternoon ahead.
Where this is taught
The Shulchan Aruch, in Orach Chaim 233, sets chatzot as a hinge of the day's prayers: Shacharit, the morning service, should be completed before it, and Minchah, the afternoon service, may be said from shortly after. This is why the Jewish day cannot be run by a wristwatch alone — the prayers answer to the sun's real position, reckoned as solar noon rather than a fixed hour.
What to do
Notice the two edges chatzot draws. Try to finish the morning Shema and Amidah before it, and know that once it passes, the time for Minchah has opened. If your morning is running long, chatzot is the line to watch. Check when solar noon actually falls for your city today — it is rarely 12:00 — and let it, not the clock, tell you which prayer belongs to the hour.
Source: Shulchan Aruch, Orach Chaim 233.
Kimá — the Jewish clock: your city's zmanim and candle times — marks solar noon for your exact place, so you always know which side of chatzot the day is on.
Open Kimá