The U.S. Forest Service has issued a warning regarding an increase in rattlesnake sightings in Southern California, especially after two deadly bites were reported in the last few weeks. 

In a social media post, the USFS San Bernardino National Forest rangers reminded hikers and outdoor enthusiasts to be wary while exploring nature due to the increased temperatures and arrival of spring weather. 

“As temperatures rise, rattlesnakes become more active in the forest,” the USFS’s post said. ” Stay alert, watch where you step and keep pets close.”

Southern California encounters

Since the beginning of the year, hikers have already reported rattlesnake encounters near a Moreno Valley hiking trail in Riverside County, where someone was bitten and required hospitalization. 

There have been deadly incidents reported in both Orange County, where a man was bitten while mountain biking in Irvine, and Ventura County, where a 46-year-old woman died from “rattlesnake venom toxicity in an accidental manner.”

“If you encounter a rattlesnake, give it plenty of space and calmly move away,” the social media post said. “Never attempt to touch or disturb wildlife.”

USFS officials credited the increase in encounters to elevated temperatures and abnormally sunny conditions as opposed to the typical winter weather that Southern California sees. 

They said that snakes can use their full length to strike, sometimes equating to more than five feet. 

Treating rattlesnake bites

Officials advised anyone bitten by a rattlesnake to:

• call 911 and seek immediate medical attention
• keep the bite victim still as movement allows venom to spread through the body more easily
• keep the injured body part motionless and lower than heart level
• keep the victim warm and at rest
• refraining from food and drink
• cover the bite with a clean, dry dressing

They also urged people to avoid using a tourniquet, slashing at the wound with a knife, sucking out the venom, using ice or immersing the wound in water, drinking alcohol as a painkiller or drinking caffeinated beverages. 

Officials warned that people should not wait for symptoms of a bite to appear before seeking medical attention. However, they provided a list of different signs that someone may see if they are bitten by a rattler, including:

• puncture marks at the wound
• redness and swelling around the bite
• severe pain at the site of the bite
• nausea and vomiting
• labored breathing
• disturbed vision
• increased sweating and salivation
• numbness or tingling in the face and/or limbs

Spotting and avoiding rattlesnakes

While Southern California is home to several species of rattlesnake, the most common are typically the Western Diamondback and Southern Pacific Rattlesnakes, according to the California Department of Fish and Wildlife. 

Aside from their infamous rattle, rattlesnakes can be identified by their broad and diamond-shaped head. They usually have spotched markings that appaer separated by lighter colored stripes that become smaller and narrower towards the tail, which is tipped with a paper-like noise-producing rattle, USFS officials said. 

While they typically hide during the cold winter months, snakes venture out during warm weather. They usually hide in shady spots during the hottest parts of the day and begin hunting either in the early morning or evening. Officials advised that rattlesnakes can swim as well. 

In order to avoid rattlesnakes, USFS rangers said that people should not tease or harass any wildlife, keep a distance of at least six feet if a rattler is spotted, stay on trails and watch where stepping or placing your hands when hiking or climbing over obstacles, avoid tall grass and piles of leaves and wear long pants and proper foot gear. 

How Many More Records Could Fall This Week?

The most prolific March heat wave in at least 14 years has already smashed monthly records in almost 180 cities from the Southwest to the Plains and East, and will have staying power in the Southwest and Plains this week.

(MAP: Temperatures Right Now)

First, let’s recap the incredible records we’ve seen shattered so far. Then we’ll look and see how long this heat will last.

New US March Heat Record

Before this heat wave, the hottest March temperature on record anywhere in the U.S. had been 108 degrees in Rio Grande City, Texas, on March 30, 1954, and on March 14, 1902.

But at least one location in the U.S. tied or exceeded that March national record four days in a row from March 18 through 21.

On March 20, four reporting stations in the lower deserts of southeast California and southwest Arizona hit 112 degrees, shown in the map below. You can’t make it up that one of these stations was near the town of Winterhaven.

These highs were only one degree shy of tying the April U.S. record high set at Death Valley, California, according to weather historian Christopher Burt. And that happened in late April — April 22, 2012 and April 24, 1946.

March Statewide Records

It also appears that the hottest March temperatures on record in 14 states were either tied or broken.

We touched on the California and Arizona records above (112 degrees) as national records, but among some other state records that appear to have been tied or set include:

• Nevada: 106 degrees on March 21
• Colorado: 96 degrees on March 21
• Nebraska: 99 degrees on March 21
• Missouri: 97 degrees on March 21
• Minnesota: 88 degrees on March 21

The other states are shown on the map below.

For bigger state or national records like these, an ad hoc committee of meteorologists and climatologists is usually convened to examine the data and the reporting station before it becomes a new, official record.

City March Records

Almost 180 locations with data since the 1960s or earlier have tied or set new March records from California to Pennsylvania to South Carolina during this heat wave.

Some of those records are shown in the map below from NOAA’s Weather Prediction Center.

Phoenix only had one March day of triple digit heat on record prior to this heat wave. They hit the 100s seven days in a row from March 18-24, topping out at 105 degrees on March 20 and 21. Incredibly, that’s equal to their April monthly record, which was set almost a month later in the calendar on three dates ranging from April 20-29 in three past years.

Other major cities that tied or set new March records included San Francisco’s first March 90-degree high downtown, Las Vegas (97 degrees), Salt Lake City (84 degrees), Boise (83 degrees) and Denver (85 or 86 degrees for three straight days).

It wasn’t just a western heat wave.

March records were tied or set in Lubbock, Texas (98 degrees), Kansas City (93 degrees), Des Moines, Iowa (91 degrees), Nashville, Tennessee (89 degrees), Louisville, Kentucky (89 degrees), Indianapolis, Indiana (88 degrees), Columbus, Ohio (86 degrees), Pittsburgh (84 degrees), and Charleston, South Carolina (90 degrees).

Perhaps the most extraordinary record heat east of the Rockies happened in Nebraska on March 21.

Both Lincoln and Omaha not only demolished their March record, after reaching 97 degrees in Lincoln and 96 in Omaha, but it also tied their April record.

Several of these cities reached the 80s, 90s, or 100s for the first time in their recorded history.

Last weekend, parts of the Plains, were as much as 45 degrees warmer than average.

This is likely the most significant, long-lived March heat wave the nation has experienced since the March 2012 heat wave rewrote the record books in the central U.S. and Canada.

There’s Still More Ahead In This Heat Wave

This heat wave isn’t over.

Another pulse of heat is surging into parts of the Plains and South this week, while continuing to bake the Southwest.

We’re expecting many dozen more daily record highs from California possibly as far east as parts of Georgia and the Carolinas.

Incredibly, some new March records could be set in a few areas, though last week’s heat set a much higher bar.

Some cities that could once again flirt with March record highs include Cheyenne, Denver and Amarillo. On Thursday, St. Louis could approach its March record (92 degrees) on Opening Day, no less, a record set 97 years ago.

(MORE: Heat Safety And Preparation)

How hot are we talking about?

Triple-digit highs: Parts of the Desert Southwest, including Phoenix, and the lower Colorado River Valley could again see triple digit heat through much of this week. A few of the hottest spots in western Texas, possibly southwest Oklahoma, could reach 100 degrees around Thursday.

90s: This searing heat will spread out from the Desert Southwest into the Plains from Nebraska to Texas to parts of the mid-Mississippi Valley through Thursday.

(MAPS: 10-Day US Forecast Highs, Lows)

Relief?

Yes, there is finally relief in sight.

A late week cold front should remove the heat from the Plains and Rockies, however, above-average warmth will rebuild back into the Plains, South and Midwest this weekend.

The Southwest will have to be more patient. While daily record warmth is possible through the weekend, a pattern of somewhat cooler temperatures, even some rain and showers are possible in the West, including California and Arizona, next week.

Why So Hot So Soon?

The reason for this heat wave in particular has to do with the ridge of high pressure, also known as a heat dome, that was parked over the West.

This heat dome is record-breaking for March, comparable in strength to ones we see in June. You can see the general position of the high pressure on the satellite loop below in the darker shading.

Jonathan Erdman is a senior meteorologist at weather.com and has been covering national and international weather since 1996. Extreme and bizarre weather are his favorite topics. Reach out to him on Bluesky, X (formerly Twitter) and Facebook.

At least a dozen candidates for governor are seeking a top-two spot in the June California Primary to advance to the general election in November. But some of them were not invited to participate in a debate at the University of Southern California. Lauren Toms reports.