Overgeneralization is a type of argumentation where we state something, giving it a property and extending it to a large population (exaggerating something claiming it is in a certain way; always, for everybody, even if it is not probably like that) and it can be based on common sense or general knowledge, a distorted notion, or the opinion of the speaker rather than to a logical and rational proof. Based on a single fact is drawn many conclusions.
"It is always hot in Brazil" could be an example of an overgeneralization.