Times of Salaat

There are 5 times of obligatory (Farz) Salaat:

1.Time of Fajr (Dawn Salaat) It starts from true dawn daybreak, when a horizontal whiteness
appears on the horizon until a little before sunrise.

2.Time of Zuhr (Noon Salaat) It starts when the sun passes its meridian (zenith after
Zawwal) and ends when the shadow of an object doubles.

3.Time of Asr (Late afternoon Salaat) It starts when the shadow of an object doubles and ends at
sunset.

4.Time of Magrib (Sunset Salaat) Begins at sunset until all whiteness disappears from the
horizon. (approximately 1 hr. 20 minutes after sunset)

5.Time of Isha and Witr (Evening and Witr Salaat) Starts from when all redness disappears from the horizon until True Dawn (daybreak).

The Witr cannot be read before Esha since the sequence is necessary to maintain.

One performing Haj can combine the Zuhr and Asr on the plain of Arafat during the time of Zuhr on condition that he is in Ihraam and the Jamaat is led by the Ameer of Haj.

The Haji should combine the Magrib and Esha at the time of
Isha when in Muzdalifah.

 It is not permissible for the Haji to perform the Magrib on route to Muzdalifah.

 Preferred Slaat tims 
1.It is Mustahab (preferable, praiseworthy) for men to perform Fajr when there is more brightness in the sky.

 For women it is Mustahab when it is not yet bright.

2.In summer Salaat should be performed at a time when the day is cooler, and should hasten it in winter, except when it is overcast.

3.To delay the Asr as long as the sun does not change color
(becomes yellow).

 To delay more than this is highly disliked. In overcast conditions Asr should be hastened (read earlier than its preferred time).

4.Magrib should also be hastened except when overcast.

5.Similarly, Isha is to be delayed up to the first third (1/3) of the night but hastened when overcast.

 To delay until midnight is permissible but after this it is highly disliked.

6.To delay the Witr to the last part of the night on condition that one is certain of awakening at that time.

Prohibited Sallat time

There are 3 times during which no Fardh or Wajib (which became due upon person before the start of these times), Salaat can be performed.

1. From sunrise to after it has risen.

2. When the sun is at its zenith at midday until it shifts from its position.

3. When the sun turns yellow until it sets.

However, those Salaats, which becomes incumbent during these times can be performed within them, but will be Makrooh (undesirable).

1. Janaazah Salaat once it is ready.

2. Sajdah Tilawat of an Ayat recited in these times. Likewise it is valid although, Makrooh to perform the Asr of the same day after the sun turns yellow.

In the prohibited times all Nafl (optional) Salaats are Makrooh Tahrimi (highly detested) even though they have some cause.

a. An oath was taken to perform the Salaat.

b. The 2 Rakaats, which become necessary after performing Tawaaf.

source: Taleem ud Deen (Hanafi), Mufti Afzal Hoosen Elias.