United States Border Patrol agents process migrants who crossed the US-Mexico border into the United States in Roma, Texas, on July 9, 2021.
Washington CNN  — 

Federal authorities in July arrested tens of thousands of migrants attempting to enter the United States from Mexico, likely surpassing June’s numbers that were the highest in decades, raising new health and safety concerns during summer’s hottest days.

Customs and Border Protection apprehended more than 176,000 migrants from July 1-28, according to preliminary data obtained by CNN – marking the highest number of arrests in July since at least 2000.

The latest border arrest data represents a continuing challenge for the Biden administration, which has struggled with a rise in unlawful border crossings that have accelerated since President Joe Biden took office.

“We certainly have a challenge at the border,” Homeland Security Secretary Alejandro Mayorkas said Monday during an interview on MSNBC.

The rising numbers come amid the hottest weeks of the summer, putting migrants in dangerous and sometimes deadly circumstances.

“It’s the hottest part of the summer and apprehensions are skyrocketing!” tweeted US Border Patrol’s Rio Grande Valley Chief Patrol Agent Brian Hastings on July 25.

A CBP spokesperson declined to comment on the data until it us officially released by the agency, but told CNN that as temperatures continue to rise in the Southwest, US Border Patrol is still encountering large numbers of migrants crossing the border into the United States.

“Migrants are often desperate for food and water as soon as they are encountered, as they underestimate the high temperatures and don’t carry enough supplies with them. USBP agents do their best to quickly rescue migrants and transport them to safe locations,” the spokesperson said in a statement.

“CBP’s message for anyone who is thinking of entering the United States illegally along the Southwest border is simple: don’t do it,” the spokesperson added, warning that when migrants cross the border illegally, they put their lives in peril and calling the summer heat “severe.”

Migrants have died of died of dehydration, starvation and heat stroke, according to CBP.

The agency conducted more than 9,000 rescues in the current fiscal year, which ends in September, as compared with approximately 5,000 rescues in all of last fiscal year 2020.

Migrants are urged to call 911 if they find themselves in distress and need to be rescued, CBP said, which can kick off an intensive process of trying to locate the person who is lost.

In south Texas, Border Patrol has also obtained GPS coordinates for over 22,000 landmarks that a lost or distressed migrant can provide to help identify their location.

The agency plans to expand the program the entire length of the southwest border, according to the spokesperson.

Hastings has been raising alarms about the danger migrants are facing in south Texas, calling attention to the high number of large groups crossing the border.

On Sunday, he wrote that migrants are in “dire need of medical care as they continually cross into the US,” including two pregnant women “suffering labor pains on Saturday.”

Last week, his agents uncovered four migrants inside a plastic tote and another rolled within carpet padding.

The temperature was 102 degrees.