Does the weather affect Shadows in Palaces?
The game makes it quite clear that adverse weather affects the Shadows in Mementos, whether it makes them more likely to call for backup, have Treasure Demons appear, or enter the battle despaired. However, the fact that it specifies the Shadows in Mementos led me to believe that it only affects those Shadows.
While rushing through the third Palace on a rainy day (no one was available to hang out, so it seemed like the best time to go), I encountered 3-4 Queen's Necklaces, which is roughly 3-4 more Treasure Demons than I usually encounter when exploring a Palace. I know that Rainy days increase the chance of rare Shadows appearing, but I thought that was only for Mementos. Does the weather affect Shadows in Palaces, as well?
21 Answer
Rain /Storms
No effect in Palace
Heat Wave
Enemies may start battle with Burn status ailment. Use Garu or Frei magic to inflict Technical damage.
Flu Season
Enemies may suffer from the Despair status ailment (death after three turns) from the start of battle. Use Psi magic to inflict Technical damage.
There is a spoiler available for the end part of the game dealing with Flu Season - be careful when researching about the end of that.
Pollen Warning
Enemies in Momentos / Palaces are more likely to be asleep, making sneak attacks (and combat in general) easier. Any kind of attack will result in Technical damage for a sleeping enemy. Enemies will ask for Eye Drops during Negotiation.