LITTLE ROCK, Ark. (AP) — All Arkansas counties are now under heat advisories as hot and humid conditions stay put in the state.

The National Weather Service says high temperatures will reach the upper 90s in some areas Thursday with heat index values of about 105 degrees. The heat advisories are in effect Thursday and Friday.

Forecasters say an upper-level ridge of high pressure will weaken this weekend, and some areas could see showers and thunderstorms on Saturday. Temperatures could dip a bit but will remain hot.

Forecasters say the hottest temperatures this week are to the north of Arkansas, with excessive heat warnings in effect in parts of Illinois, Iowa, Kansas, Missouri and Nebraska. In those states, the heat index value could reach 110 degrees.