When it hits
Day 38 at 08:00 on the Warehouse Manager's run
No warning comes first.
Starts with Continuous Rain, ends with 
Rain Clears.
The same on every run: Wage Slave, Student
What comes
No zombies: this crisis is about the weather, sickness or pests, not a siege.
From the game files1
Crisis 148
| id | 148 |
|---|---|
| CrisisID | 148 |
| StartEvent | [62665] |
| EndEvent | [62666] |
| Des | Crisis_Des_201 |
| Des_Local | 阴雨 |