Families with kidsSummer (July–August) is best so they can start the new school year in September.
Singles or couples without kidsSpring or Fall (April–May or October–November) is easier for housing, flights, and ulpan availability.
Winter (Dec–Feb) is quieter and may mean shorter wait times for appointments.
I made Aliyah in early September—hot, but smooth. Bonus tip: flight prices spike in August, so book early or choose shoulder seasons if you’re flexible.