Can I cover the vents ?

[Fabian]

My house has gable attic vents in the corners.
Even though they are covered with screens, some snow blows in on to the insulation.
Should I just staple some foil or film over the vents during winter?

[home improvement guy]

You shouldn't cover the vents. Attic ventilation is important during winter so moisture coming up from the house doesn't condense in the cold attic. Damp insulation loses much of its insulating effectiveness.

Place plastic film over the insulation near the vents to catch the snow. It will melt and evaporate over time.

Next spring, consider installing more effective soffit vents and a ridge vent.