Typhoon figures are 1991–2020 averages. From the Japan Meteorological Agency (JMA).
Tsuyu is a seasonal event as spring changes into summer. There is more rain and less sunshine than in the weeks before and after.
On average, the start and the end of tsuyu each take about five days to change over. The JMA gives the date near the middle of that change.
The JMA first announces the start and end quickly, based on forecasts. After the season, it looks back at the actual weather and fixes the dates. It keeps these fixed dates for 12 regions, from Okinawa to northern Tohoku, going back to 1951.
A typhoon is a tropical low-pressure system in the northwest Pacific (north of the equator and west of 180° east) or the South China Sea, with top winds (10-minute average) of about 17 m/s (34 knots) or more.
Typhoons grow on the heat that is set free when water vapor from the warm sea turns into cloud droplets.
At low latitudes, typhoons usually move west. They then move north around the Pacific High, and when they reach the westerlies, they speed up toward the northeast.
From 1991 to 2020, an average of 25.1 typhoons formed each year. The most formed in August (5.7), then September (5.0).
An average of 11.7 a year came close to Japan, which means the center came within 300 km of a weather station. An average of 3.0 made landfall, which means the center reached the coast of Hokkaido, Honshu, Shikoku or Kyushu.
The JMA numbers typhoons from No. 1 each year, starting with the first to form after January 1.
Since 2000, typhoons have also had Asian names. The Typhoon Committee, whose members include Japan and 13 other countries and areas, uses names proposed by its members. The 140 names are used in order. The first was “Damrey”, meaning elephant, from Cambodia.
Japan proposed 10 of the names, all taken from constellations, because they are neutral, come from nature, and are linked in people’s minds with the sky.
There is no single right answer. Talking it over with someone at home is a good way to learn.