Chicago Public Schools canceled Wednesday classes amid sub-zero predicted temps.

The school system joins a growing number of school districts in the region that already have canceled classes.

The National Weather Service warns of dangerously cold wind chills from Tuesday night through Thursday morning, bottoming out at 35 below zero overnight and into Wednesday morning. Wednesday will feel only slightly warmer — with wind chill temperatures about 25 below zero, according to the service.

That means frostbite could occur as quickly as 15 minutes on skin exposed to the cold.

Bitter cold sets in after snow blankets Chicago area

CPS CEO Barbara Byrd-Bennett said in a statement: “The safety and well-being of our students comes first. The frigid temperatures and winds make a dangerous combination, and it is in the best interest of our students to cancel classes.”

Although classes are canceled, CPS buildings will be open to students who arrive at their schools. CPS administrators, engineers and custodians will report to work on Wednesday.

Last year, CPS shut down for four days in January because of frigid temperatures and snow, making the days up in March and at the end of the year.

Also closed in Chicago are the Noble Network of Charter Schools and the UNO Charter Schools.

Meanwhile, the following suburban districts have also canceled classes for Wednesday:

Community Unit School District 308

Community Consolidated School District 21

River Trails School District 26

School District 54 in Schaumburg Township

East Maine District 63

Park Ridge-Niles School District 64

Norridge School District 80

Cook County School District 104

Willow Springs School District 108

Lake Park High School District 108

Indian Springs School District 109

Deerfield Public School District 109

Burbank School District 111

Township High School District 113

Lemont-Bromberek District 113A

North Palos School District 117

Palos School District 118

New Lenox School District 122

Ridgeland School District 122

Oak Lawn-Hometown School District 123

Evergreen Park Elementary School District 124

Atwood Heights School District 125

Alsip, Hazelgreen & Oak Lawn District 126

Palos Heights School District 128

School District 129

Cook County School District 130

Calumet Public School District 132

Riverdale District 133

Orland School District 135

Kirby School District 140

Forest Ridge Elementary School District 142

Midlothian School District 143

Posen-Robbins School District 143 1/2

Prairie-Hills School District 144

Arbor Park School District 145

Community Consolidated School District 146

South Holland School District 150

Hazel Crest 152 ½

Hoover-Schrum Memorial School District 157

Lansing School District 158

Elementary School District 159

Matteson School District 162

Park Forest- Chicago Heights School District 163

Community Consolidated School Districts 168

Ford Heights School District 169

Chicago Heights District 170

Sunnybrook School District 171

Burr Ridge Community Consolidated School District 180

Plainfield Community Consolidated School District 202

Indian Prairie School District 204

Thornton Township High School District 205

Bloom Township District 206

Maine Township High School District 207

Township High School District 211

Leyden High School District 212

High School District 214

Argo Community High School District 217

Community High School District 218

Barrington School District 220

Bremen Community High School District 228

Oak Lawn Community  High School District 229

Consolidated High School District 230

Valley View School District 365U

Also closed: The DuSable Museum of African American History