Weather is the trigger nobody can avoid and almost nobody logs. VertigoMe pulls it for your city every day, plots it against your spin days, flags a barometric drop on the home screen, and shows the week ahead so a pressure fall is visible before it arrives.

Across 56 patients and about nine months of daily diaries, the change in air pressure over the preceding day was significantly associated with the odds of a Ménière episode.
Gürkov et al., PLoS One 2016Pressure for your city is stored every day and plotted under Monitor and Environment with your spins marked. Pressure high and pressure low are automatic triggers. Separately, the home screen compares today's low with yesterday's mean and shows a Barometric pressure alert card when the drop is 10 hPa or more.
A daily server check at 9 in the morning looks at the overnight drop for your city and, if it is 10 hPa or more and you have left Pressure drop alert switched on in Notifications, sends a push. It is a once-a-day check against stored daily values, not a live barometer, and you can switch it off.
The 7-Day Forecast card lists the coming days' pressure, temperature and conditions for your city, which is how a fall due later in the week is visible today. The risk outlook uses the same days, so weather triggers due ahead show up there as well. The forecast card is part of Premium.
Altitude and altitude change are read from your location and fire as triggers on their own, so a mountain weekend or a flight does not slip past. Travel, jet lag and recent illness are in the manual set, one tap each. Location is city level only.
Monitor and then Environment. The day's conditions at the top, a metric list for temperature, pressure, humidity, wind speed, UV index, altitude and altitude change, and the history with your spins laid over it. The 7-Day Forecast card sits under it, and the pressure drop alert appears on Home on the day it fires.
Location, at city level only, never your exact address, and used for weather and altitude alone. Skip it and the weather layer stays empty while everything else carries on. The push that goes with the pressure alert is optional; neither it nor the forecast claims to predict a spin.
Barometric pressure, temperature, humidity, wind, UV index, thunderstorm days, altitude and altitude change.
The 7-Day Forecast card shows the coming days, and the pressure drop alert fires on the day itself, on the home screen and as an optional push. Neither says whether you will have a spin; they tell you what the weather is doing.
Weather needs it. You can skip it, but then the weather layer stays empty. Only city-level location is collected.