When this scene opens, the mood is both unsettled and agitated. It is a hot day, for example, and Benvolio wants to avoid a meeting with the Capulets because a fight is certain to break out.
Benvolio's fears are soon confirmed. Tybalt, a Capulet, suddenly appears, and the mood quickly becomes tense. Tybalt says he is looking for Romeo but his words prompt Mercutio to touch his sword, a sign that he is ready to fight.
Romeo's arrival does little to alter the tense mood. Mercutio and Tybalt begin fighting and the mood switches to one of violence. Mercutio's death maintains this violent mood: Romeo takes revenge by killing Tybalt.
The mood briefly switches to one of sadness at Lady Capulet mourns the death of her nephew. But, this does not last: the mood grows angry and tense, once again, as the Prince declares that Romeo is banished from the city for the murder of Tybalt.