KITCHENER -- The drive-thru COVID-19 testing clinic at Grand River Hospital closed Tuesday due to heavy rains throughout the morning.

People who were already in line waiting to be tested were able to get their tests done, but the gate was closed to new arrivals around 11 a.m.

Environment Canada had called for showers throughout the morning, ending in the afternoon but maintaining a 60 per cent chance to return.

That forecast also included a risk of thunderstorms, which continues through the nighttime.

A spokesperson for the hospital says that the site was closed because the heavy flooding caused some flooding at the site, and because there was lightning.

"We made the decision to close today to ensure the safety of our staff and physicians, as well as our residents," the spokesperson said in an email.

Environment Canada is also forecasting a chance of rain on Wednesday, Thursday and Saturday. The hospital says it will monitor the weather each day to assess whether or not testing can go ahead.

The drive-thru testing centre has the capacity to test between 300 and 350 people per day. There's also a walk-up option for people who don't have access to a vehicle.

Regional public health officials have reported a huge spike in testing over the last few days, with nearly 4,000 tests being reported from Friday to Monday, and another 1,249 tests on Tuesday. That's out of a total of 30,516 tests done to date.

There have been nearly 30 cases of COVID-19 reported in Waterloo Region since Friday, though the number of active cases in the region remains below 90.

Public health officials haven't reported a death associated with the virus since June 3. A total of 115 people in Waterloo Region have died from the virus.