Weather sentences need a det that stands for nobody: det regner, det sner, det er skyet. Hvis opens a subordinate clause, and when that clause comes first the main verb follows straight after the comma, keeping the verb in second position overall.
Examples
- Det har regnet siden i morges.
- It has been raining since this morning.
- Hvis det regner i morgen, bliver vi hjemme.
- If it rains tomorrow, we will stay at home.
- Jeg tager en paraply med, hvis det er skyet.
- I will take an umbrella if it is cloudy.
The mistake to avoid
The det cannot be dropped: det regner, never just "regner".
Where this fits in
Planer og aftaler, Danish A2: Foreslå noget, aftale og flytte en tid, og tale om vejret, der ændrer planerne.