Germany will reach more than 400 in September if case numbers keep rising at their current pace, Health Minister Jens Spahn said on Wednesday.
After more than two months of steady decline, Germany's 7-day incidence, at 11.4 per 100,000 on Wednesday, has risen since early July due to the spread of the more infectious Delta variant.
More than 50 million people in Germany - 60% of the population - have received at least one shot of vaccine against the virus, Spahn said.
Around 47% are fully vaccinated. The German cabinet on Wednesday extended Covid-19 quarantine regulations for incoming travellers from higher-risk areas until mid-September.