Does the weather affect Shadows in Palaces?

Solution 1:

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.