I'm out in it twice a week right now for my son's soccer games.
We are out till 9-10 pm
Is that all?
We are not talking here about a few hours watching soccer games (which finish before 10pm), before heading indoors to a warm bed. That is quite a different situation to sleeping out on bare ground, all night and every night, during which the pre-dawn grass temperatures often approach freezing.
The Met Service's 24 hour temperature charts only confirm what any of us who have worked night shifts in outdoor conditions (and in a variety of different climates) have already learned from experience
- i.e. The coldest temperatures of the day occur just after first light of a morning.
Furthermore, its effect on human physiology is exarcerbated by the body's Circadian Rhythms, which are at their lowest ebb around 2:30 am. Again, shiftworkers quickly find out all about that phenomenon.
To use the old expression, "You ain't seen nothing yet" when you call it a night before 10pm.
Of course, all the foregoing assumes that the climate of Israel was the same 2000 years ago as it is now.
In fact, Climate Change is not at all a recent phenomenon.
Certain passages of scripture, together with archeological research strongly suggest that Israel's climate was once both cooler and wetter than it is now. After the time of Christ, a process of gradual desertification set in. This was hastened by the denuding of Israel's once extensive forest cover - a process that continued into the early 20th Century. (Removal of the forest cover is a near-certain way of reducing rainfall, as they are presently learning in the Amazon Basin).
It is assuming a lot to take for granted that Bethlehem's climate was the same then as it is now. In all likelihood, those shepherds the Gospels talk about would have encountered colder and wetter conditions than are now the rule.