The temperatures across California have soared this week due to the blistering heat, leading to millions of peopleswitching on their air conditioning units to stay cool.

However, this surge in use of power-hungry appliances has led to a severe strain on the state’s electrical grid, as seen in a grid usage tracker by the California Independent System Operator.

The California Independent System Operator (ISO) has issued a Flex Alert every day for the past week, asking Californians to conserve energy and minimize their power use in order to avoid overloading the grid.

The available capacity for the state is about 51,000 megawatts. According to KCRA, California ISO said its power grid peaked at 52,061 megawatts on September 6, which is its all-time record high.

Temperatures have soared to record highs across the state.

In Bay Area cities Livermore and Fairfield, temperatures were recorded at 116 degrees Fahrenheit. Hot weather can be deadly if people cannot get cool: heat is responsible for more deaths worldwide than all other extreme weather events.

Therefore, people all over the state are turning their AC units to full, using up vast amounts of electricity in the process, pushing the grid to its limits.

Intense temperatures can actually make wires less efficient at moving electricity, further exacerbating the strain on the grid. Additionally, the heatwave means that transformers and power plants themselves need air conditioning, again increasing the energy usage.

“We designed the grid and wrote reliability requirements for the 20th century,” Mark Dyson, managing director of the Carbon-Free Electricity Program at RMI, a clean energy think tank, told Vox. “We didn’t know that the weather was going to get a lot more extreme, both cold and hot. And what we’re seeing in particular is large, aging fossil fuel plants showing their weaknesses.”

Lake Mead and Lake Powell on the Colorado River, the country’s largest reservoirs, are both drier than they have ever been, and are inching toward dead pool level due to the drought that has been scorching them for years.

When their water levels drop to this dead pool level, the flow of water from the reservoir through the Hoover and Glen Canyon dams hydroelectric turbines will stop, meaning that both dams will no longer be able to generate power for California, Arizona, Nevada and parts of northern Mexico.

In a video message, Democratic Governor Gavin Newsom warned residents that “the risk for outages is real and it’s immediate.”

“This heatwave is on track to be both the hottest and the longest on record for the state and many parts of the West for the month of September. Everyone has to do their part to help step up for just a few more days.”

California residents can track their local energy demand using the California ISO’s tracker, which shows how close to capacity the power grid is, and the forecasted peaks in the coming hours and days.

If demand on the grid is expected to exceed capacity, the state may trigger rolling blackouts. While no blackouts were announced on September 6, as of 11pm, 50,000 customers were without power across California.

No blackouts are forecasted for the rest of the week. However, the heatwave is expected to remain in full force until September 9, according to ABC30.