Thunderstorm

Thunderstorms are an uncommon event that occurs when wind speed reaches 20mph and rain level is at 50%, and continues until either wind speed drops to 15mph or rain level drops to 40%. Occasionally, lightning will strike, lighting up the player's screen on surface. This is accompanied by thunder, during or after the flash. Even though it appears to be windy, kites act as if there is no wind present. Lightning bolts cannot strike the player, even if it has a kite or an umbrella equipped.

All surface music will be changed to Storm.

NPCs have special dialog during thunderstorms, however, no new monsters will spawn while the event is active, contrary to the Guide's quotes. (Verify)

On older Mobile Versions, thunder will show up sometimes when it rains. This is unlike the Thunderstorms on the Desktop version, however, as it is not a different event, and no unique monsters spawn during it.