That Day's Weather

Do you remember the sky that day?

July 14, 1998, Fukuoka: sunny. High 29.2°C, low 21.9°C.
Give it a date and a place in Japan, and it shows you the weather that was actually observed that day.

This is not a forecast app. It's for looking back at days that have already passed.

■ For days like these

Birthdays, wedding anniversaries, the day your child was born, a trip, the day you first met.
Enter the date and place, and that day's sky appears.

For every day you save, past years on the same date are lined up year by year.
How many times it was sunny, how many times it rained, and what the average temperature was.
Recent years are free. Going back further requires an in-app purchase.

■ Today will be "that day" someday

See today's weather side by side with past years on the same date.
An ordinary today will one day be a day worth looking back on.

■ Where the weather comes from

Historical observation records published by the Japan Meteorological Agency. Not forecasts or estimates, but values recorded at weather stations on that day.
When you choose a place, the app picks the nearest station that records both temperature and sunshine.

Once fetched, the weather stays on your device, so it opens without a connection next time.

■ What it can't do

・Records are for places in Japan only. Places outside Japan have no weather
・Before 1961, sunny and cloudy can't be told apart, because sunshine records hadn't started yet. Rain and snow can still be determined from temperature and precipitation
・Some items weren't observed, and some days have no surviving record. Those days show as "Unknown"

Temperatures alone go back to the Meiji era (late 1800s) at some stations.
The temperature on the day your grandparents were born may still be on record.

■ About purchases

Recent years are free to use. Plans let you go back further, see the calendar for every month, and get stats across all years.

Choose Monthly (auto-renewing), Yearly (auto-renewing), or Lifetime (one-time purchase). Prices are shown in the store and in the app before you buy.
Auto-renewing plans renew automatically unless cancelled at least 24 hours before the end of the current period.
You can cancel in your device's store settings.

Terms of use: https://tsumuchan.notion.site/82ae7d6a0abd83ee8deb01a402addfc0
Privacy policy: https://tsumuchan.notion.site/1c4e7d6a0abd825e9b7e81fbc8e1338d

■ Your data

Your records stay on this device only. No account, no sign-in.
When you switch devices, export a file from Settings and import it on the new device.

Source: Japan Meteorological Agency website (historical weather data)