I believe that extreme weather deactivates any current weather boosts and may very well force any weather boosted mons to despawn. The other night I was checking an area near where I live that's well known for spawning tons of Machops during cloudy weather. When I got there, 3 Machops popped up with a variety of other Mons in one of the clusters. I shiny-checked an Aron first, and after fleeing the encounter, I got hit with the "extreme weather" message. And then, bam, all 3 Machops were gone. Most of the Mons in that cluster were still there, with the exception of the previously weather boosted Mons (the Machops, a Clefairy, and a couple Gulpin).
GamePress
Extreme weather warning kills spawns?
Disclaimer: This involves knowledge only attainable using an IV scanner. If you don't play with a scanner because you feel it's cheating, that's not the purpose of this question and please discuss your objections to it elsewhere. I don't want to start a debate on whether or not scanners are a legitimate tool for players to use.
It's been well-documented that when the weather changes, if a Pokemon was boosted and becomes not-boosted (or vice versa), the IVs are re-rolled while the level changes -/+ 5 levels, respectively. In effect this translates to being wary about chasing spawns when the hour is about to change. However, I had an experience tonight where I believe an extreme weather notification in-game changed a spawn's species and IVs, while the weather stayed the same. The notification came at around 12:15AM (I think) and I was out looking for the Machop in question at around 12:30. There are two different scanners for my area and both tracked the Machop and showed no change, which isn't surprising because they don't typically update existing spawns when the weather changes. This is the first time I've seen or heard of an extreme weather warning kill a spawn, though. The weather in my area right now is completely calm, although we are expecting a storm tomorrow.
Has anyone else had this experience as well? Obviously it's frustrating to lose a spawn to the whims of Pokemon Go weather changes (second time that has happened to me in 2 days, in fact, although yesterday it was from a seemingly unjustified shift from clear to windy at the top of the hour), but I'm more curious to see if this is a more general phenomenon.
Report
Answers
That sounds exactly like what happened to me. Very annoying because it's kind of hard to predict exactly when the warning is going to pop up, whereas the weather change at the top of the hour can be somewhat predicted.
Boosted Pokemon continued to spawn after the weather warning, so it seems like a one-time re-roll of existing boosted spawns is what happens when a warning pops up the first time.
Huh. That is definitely what the "extreme weather" warning did when the weather system was first introduced. In fact my first week of the weather system was predominantly "extreme weather" with no weather bonus and fewer spawns because I think some spawn points are dedicated to weather.
After the first week or two though they toned down the "extreme weather" which cancels out all weather, and the red banner "hazardous weather alert" became the more common warning. The "hazardous weather alert" can be dismissed and doesn't affect weather boosted spawns.
