I took an umbrella, as it was raining. I went for a swim, because it was very hot.

[Tan Elaine]

I took an umbrella, as it was raining.
I went for a swim, because it was very hot.

Is a comma obligatory in the above sentences? Thanks.

 

[MikeNewYork]

Generally, we do not insert a comma before "because". A comma before "as" is more common because "as" functions as many parts of speech besides conjunction, and confusion can arise without a comma.