In the northern hemisphere, the longest day of the year normally occurs in the :

1. The question asks about the timing of the longest day of the year in the northern hemisphere. 2. The longest day corresponds to the summer solstice in the northern hemisphere. 3. The summer solstice occurs when the Earth's axial tilt causes the North Pole to be most inclined towards the Sun, and the Sun reaches its highest position in the sky as seen from the North Pole or Tropic of Cancer. 4. This event typically occurs on June 20th or 21st each year. 5. June 20th or 21st falls within the second half of the month of June (which spans from June 16th to June 30th). 6. Therefore, the longest day of the year normally occurs in the second half of the month of June.