Isn't Arrakis supposed to be hot?

Question

In the movie Dune, there is a lot of emphasis on how dry and sandy Arrakis is. However, isn't Arrakis supposed to be very hot? I mean, this is the main reason the Freman supposedly prefer to move outside during the night instead of the day. While watching the movie, I noticed that in every scene outside you never got the feeling that Arrakis has this hellish hot planet. After the movie I asked my daughter who has never read the book or learn about the story before, if she thought Arrakis was hot or not and based on the movie, she didn't get the impression that it was a hot place.

Edit: Indeed, it seems that in the appendix I, the book says it was a very hot place. "Kynes and his people turned their attention from these great relationships and focused now on micro-ecology. First, the climate: the sand surface often reached temperatures of 344° to 350° (absolute). A foot below ground it might be 55° cooler; a foot above ground, 25° cooler. Leaves or black shade could provide another 18° of cooling."

Answer 1

For the 2021 movie specifically, there are a handful of scenes which indicate the areas of the planet that the movie takes place in are scorching hot.

1. Shortly after they arrive on the planet when Leto and Gurney are out on the balcony overlooking the city early in the morning the guards comment that the sun is getting too high and it is time for them to seal the building for the day.
2. When Paul goes out to the courtyard with the palm trees the man watering them tells him to go inside as it is too hot at this time of day. He is also wearing a sun shade over his head and is visibly sweating. Additionally the air is visibly shimmering, an effect of the very high temperature of the ground.
3. Fremen are depicted as only traveling at night to avoid the heat of the day unless absolutely necessary. This is said overtly and also implied when at the end of the movie Stilgar tells Jamis that they need to get moving as the sun will be coming up soon.
4. In the vignette of Chani at the beginning, she describes the spice harvesters as only coming out in twilight hours to avoid the heat of the day. This does not appear to be adhered to with the trip to the spice harvester in the middle of the movie however this could be explained away in any number of ways.

Answer 2

Arrakis is an incredibly dry desert planet.

But deserts are not necessarily hellishly hot. The Gobi desert in China/Mongolia averages below freezing temperatures through the year. Antarctica is a desert, too.

Even the Sahara, which maxes out at about 47°C sees daily averages in some regions of 30°C or even lower in the winter - which might be uncomfortable in the UK where the humidity is higher, but is more tolerable in a hyper-arid environment.

Most of the action of the movie takes place at fairly high latitudes - about 60° latitude - where it will be cooler than at the equator, even in summer (assuming that Arrakis doesn't have an extreme axial tilt). From the books, we know that the planet even has (very small) polar ice caps.

So - in conclusion - Arrakis is dry and sandy, but not necessarily hot.

Answer 3

Thanks for the answers and comments so far. Based on the passage quoted from the book, I feel that indeed, Arrakis is supposed to be a hot place during the days but the film didn't really portray that aspect of the place.

"Kynes and his people turned their attention from these great relationships and focused now on micro-ecology. First, the climate: the sand surface often reached temperatures of 344° to 350° (absolute). A foot below ground it might be 55° cooler; a foot above ground, 25° cooler. Leaves or black shade could provide another 18° of cooling."