Why would Clint need to be sleeping in broad daylight?

[Jeep]

I was under the impression that it was the next morning, because the captain of the army tells his sargeant that they're "spending the night in this place," so it would make sense that they're "moving on very quietly" early the next morning.

[drinkanddestroy]

Yeah, I was under the impression that it's early in the morning, Silvanito has just woken up, TMWNN has been lying there all night in the same position and hasn't moved, when Silvanito sees that TMWNN's eyes are open, he realizes it's been like that all night. (As Frayling once said, nobody sleeps in a Leone movie  )

Remember, the cavalry was spending the night in the town, and now is leaving town quietly, they don't want to arouse any more attention than is necessary as they go to the river to make the weapons deal. Well, sneaking out quietly in the middle of the afternoon wouldn't help much! So I always understood it to be early in the morning, just as Silvanito is waking up, and he realizes that TMWNN hasn't been sleeping... and it bothers Silvanito to see TMWNN staring like that

[Yellowhead]

I was wondering about the sun's position in the sky at that point too, but like many others, I just assumed it was early morning. Or Clint decided to take a random siesta?...Doesn't Silvanito inquire why he is sleeping with /all/ of his day clothes on? Or did I misunderstand something? I found that to be a little weirder than the fact he was sleeping in what seemed like broad daylight.

And also a comment on the weather-I've lived in Tucson and Phoenix before, and I can't say that the heat is as bad as people generally make it out to be. 
I mean, obviously it gets unbearably hot during the summer (if not most of the year), but I find the humidity in some of the southeastern states to be far more devastating than anything.

Just saying 

[t-bone]

maybe he was just tired. 

[Cusser]

And also a comment on the weather-I've lived in Tucson and Phoenix before, and I can't say that the heat is as bad as people generally make it out to be. 
I mean, obviously it gets unbearably hot during the summer (if not most of the year)

I've been here in Phoenix 40 years, and it's so hot you can't breath sometimes.  Last weekend (they call it "fall") it was 106F here !!!  If I didn't have a job here, I'd be gone so fast....summer is like 9 months long...

As Tuco would say: "it's so hot you can feel the devil bite your ass !!!"

[Rudra]

Clint is not sleeping in the broad daylight neither it is the siesta, he just woke up and lying idly on the bed. If you remmeber the commander of the Mexican army instructs his sub (the previous evening) that they will be doing a night halt at San Miguel and to double the guards for stagecoach carrying gold to be exchanged for guns and ammunition with US army. The next day, the Mexican army leaves early morning that is when Silvanito sees them from the window of his room.

[Cusser]

One needs to have lived in this climate to really understand the siesta.  These people are not lazy, the heat through the day just zaps you. 

It's just unbearable to be outside in mid-day for much of the year.