A 145-year-old heat record could fall in Denver on Wednesday while poor air quality lingers in the city, the National Weather Service in Boulder said.

Denver is expected to reach a high of 99 degrees, which would break the record of 98 degrees for July 28 set in 1876, the agency said.

The record was set just days before Colorado became a state and is Denver’s oldest record high temperature. 

Sensitive groups, such as those with lung disease or asthma are advised to avoid strenuous outdoor activity before 4 p.m. because air quality will be worsened Wednesday, the weather service said.

Overnight temperatures are expected to drop to 68 degrees, the agency said.

Thursday is likely to bring another day of intense heat with rain showers likely during the weekend, the weather service said.

Here’s an extended forecast from the National Weather Service:

Thursday: Sunny and hot, with a high near 97 degrees and winds between 5 to 9 mph.

Friday: Sunny, with a high near 95 degree and winds between 5 to 10 mph. A 40% chance of showers and thunderstorms after noon. 

Saturday: Partly sunny, with a high near 84 degrees.  Showers and thunderstorms likely, mainly after noon. Chance of precipitation is 70%.

Sunday: Mostly cloudy, with a high near 78 degrees. Showers and thunderstorms likely, mainly after noon.