"In the summer, it is warm."
Translation:Pendant l'été, il fait chaud.
For a month, use en. For a decade or period, use dans. http://french.about.com/library/prepositions/bl_prep_en_vs_dans.htm
I think the reason that the question keeps getting repeated is because the answer does not seem clear. The definite article is normally used before names of seasons - for example - summer l'été, but in this case you use 'en été' because you are speaking of a period of time. Is that what you meant by your Note?
It may be useful to add that "c'est chaud/froid" here is an invariable expression regardless of gender or plurality & only refers to the temperature of something 'in general'. So in your example "In summer, it's hot [in general]", whereas "Cet été, il fait froid" means this particular summer. "The apple, it's hot" is "la pomme, elle est chaude" instead of "... c'est chaud" because we are talking about a particular apple. Would you agree?
Yes, c'est chaud/froid is an invariable expression to describe a generality. You may also use Il fait chaud to describe a generality.
You may use either "Il fait" or "C'est" in this sentence:
L'été, il fait chaud = In summer (generally), it is warm.
L'été, c'est chaud = In summer, (generally) it is warm.
La pomme, elle est chaude is correct because we are talking about a specific apple.
With temperature (hot / cold) - and some other things - you must express it using "faire" to convey the meaning. I can't explain in full why it is this way at this point in time, but I can confirm that this is the normal way to do it. "Durant" is unecessary (please see the post above) unless you wish to say "throughout", which could work fine but perhaps doesn't match the DL sentence.
What answer was that? Also, if you're still on the heart system, you might need to refresh your cache (you'll have to look up how to do that for your particular browser). That usually solves those kinds of things. Either that or they're reverted to the old heart system, and I'm the one who needs to refresh my cache.