Although the Monsoon brings welcome rains and relief from the summer heat, the thunderstorms that come with the Monsoon
bring their own hazards. In fact, this is the most dangerous time of year weather-wise in the Southwest. So before the
season gets underway, it is a very good idea to review these safety tips.
Before the Storm, check the weather forecast before leaving for extended periods outdoors. Always keep an eye to the sky
and watch for signs of approaching storms. If a storm is approaching, keep a NOAA Weather Radio or AM/FM radio with you or
a cell phone capable of browsing the web. If a Severe Thunderstorm Watch is in effect, be mindful that severe thunderstorms
could quickly develop. When a Severe Thunderstorm Warning has been issued, outdoor activities should be postponed as this
is your best way to avoid being caught in a dangerous situation.
Dust Storm Warning A dust storm, with visibilities of 1/4 mile or less, is about to strike, or
has already developed. Pull off the road now! Wind gusts between 40 and 60 mph are also likely.
A dust storm usually arrives suddenly in the form of an advancing wall of dust and debris which may be miles long and
several thousand feet high. They strike with little warning, making driving conditions hazardous. Blinding, choking dust
can quickly reduce visibility, causing accidents that may involve chain collisions, creating massive pileups. Dust storms
usually last only a few minutes, but the actions a motorist takes during the storm may be the most important of his or her life.
If dense dust is observed blowing across or approaching a roadway, pull your vehicle off the pavement as far as possible,
stop, turn off lights, set the emergency brake, take your foot off of the brake pedal to be sure the tail lights are not
illuminated. In the past, motorists driving in dust storms have pulled off the roadway, leaving lights on. Vehicles approaching
from the rear and using the advance car's lights as a guide have inadvertently left the roadway and in some instances collided
with the parked vehicle. Make sure all of your lights are off when you park off the roadway. Don't enter the dust storm area
if you can avoid it.
If you can't pull off the roadway, proceed at a speed suitable for visibility, turn on lights and sound horn occasionally.
Use the painted center line to help guide you. Look for a safe place to pull off the roadway. Never stop on the traveled
portion of the roadway.
During threatening weather listen to commercial radio or television or NOAA Weather Radio for Dust Storm Warnings. A Dust Storm
Warning means visibility of 1/2 mile or less due to blowing dust or sand.
Severe Thunderstorm Watch Conditions are favorable for widespread thunderstorms with damaging winds
and even large hail to develop. These are usually issued only when an especially active day is expected. Watch weather reports and conditions closely.
Severe Thunderstorm Warning A thunderstorm with damaging winds of 60 mph or greater is about to occur,
or is already underway. These winds could also produce a dust storm with visibilities below 1/4 mile. Hail 1" in diameter or larger
is also possible.
Unlike other parts of the country, thunderstorm wind gusts here in the Southwest almost always exceed 40 mph. The strongest
wind gusts can exceed 100 mph, and can produce damage similar to a tornado! Anytime a thunderstorm approaches, no matter how
weak it seems, move indoors to avoid flying debris. Winds rushing down from a thunderstorm can develop very quickly.
When a Severe Thunderstorm Warning is in effect, it means damaging wind gusts of 60 mph or higher are
occurring or likely. Move into a central interior room. Stay away from windows. Unanchored mobile homes are NOT safe in any
severe thunderstorm, and even anchored mobile homes can be heavily damaged in winds over 80 mph. Move to a more sturdy structure.
Stay away from trees. The vast majority of people are killed or injured in severe thunderstorms by trees falling on them,
from flying debris, or from downed power lines. Never touch a downed power line, even if it appears dead. Assume that it is
live. Call for help instead.
Straight line winds can travel dozens of miles away from the thunderstorm that produced them. If the wind suddenly shifts and
blows toward you from an approaching storm, while the temperature either becomes much colder or much hotter, the winds are
likely to become even stronger. Move indoors!
Before the monsoon season, it is a good idea to either secure loose outdoor furniture and garbage cans, or move them indoors.
These are frequently blown around in our summer thunderstorms - even the weakest ones.
Flash Flood Watch Conditions are favorable for flash flooding over large or multiple areas of
the region. These are usually issued only when an especially active day is expected. Watch weather reports and conditions closely.
Urban and Small Stream Flood Advisory Minor flooding is expected or underway in low lying and flood
prone areas. While it may not be life threatening, extreme caution is advised, particularly for motorists.
Flash Flood Warning Life-threatening, rapid flooding is about to occur, or is already underway.
Move to higher ground now! It is particularly dangerous to be in a low lying area or near a wash.
Flash floods are common in the Southwest. There are thousands of low water crossing and dips which flood every summer. Know
where they are, and avoid them during heavy rains. If you find yourself in a situation where flash flooding is occurring,
get to higher ground quickly.
Never drive into a flooded roadway. The water depth is very easy to misjudge, and the road
itself may be damaged or destroyed underneath the murky water. Be especially cautious at night when it is harder to recognize
flood dangers. It only takes about 1 to 2 feet of water to float most vehicles, including SUVs. Never drive around barricades.
They are there for a reason - usually because flash flooding is about to take place, is already happening or the road is
damaged by flooding and is unsafe. Find an alternate route or exercise patience and wait for the
flooding to subside.
Even 6 inches of fast-moving flood waters can knock you off your feet, and a depth of 2 feet will float your car. Never try
to walk, swim or drive through such swift water. Never allow children to play near washes or storm drains after any rainfall,
no matter how light. These flood easily and rapidly, and storm drains are usually so large that children can be swept away.
Beware of distant thunderstorms, especially if they're over mountains. Flash flooding can occur many miles away from the
thunderstorm as the runoff flows into the valleys and deserts.
Do not camp overnight or park your vehicle along/near streams and washes during the monsoon. Although many of our
thunderstorms occur during the afternoon and evening, some of our worst flash floods have occurred in the middle of the night.
Hikers and mountain bikers should try to get out earlier in the day to avoid the dangers of not only flash flooding, but
also lightning. Wherever you are hiking during the monsoon, be aware of your escape routes, follow ranger instructions, and
be prepared to move to higher ground quickly.
Although the monsoon is generally associated with slightly cooler temperatures and rainfall, excessive heat is still by far the
number-one, weather-related killer in the Southwest. Unfortunately, many heat-related deaths occur during the Monsoon as our
typical summertime heat is combined with increased monsoon humidity. For information on heat, go to our
Heat Safety Page.
Lightning can strikes up to 60 miles away from the nearest rainfall. If you hear thunder, you are close enough to a storm to
be struck by lightning. Go to a safe place immediately! The safest locations are sturdy buildings and hard-topped vehicles.
Wait there until 30 minutes AFTER the last rumble of thunder is heard. Get away from open areas, including armadas, porches,
trees, convertible cars, swimming pools, and open areas.
Plan outdoor activities to avoid being outside between mid afternoon and mid evening, especially in higher elevations where
lightning is more common. If you are outdoors when lightning becomes a danger, find a low spot away from trees, fences and
When indoors, do not touch any wires or plumbing inside a building. Telephone lines and metal pipes can conduct electricity.
Unplug appliances not necessary for obtaining weather information. Avoid using corded telephones or any electrical appliance.
Use phones ONLY in an emergency. Remember to bring pets indoors. Lightning and thunder are very scary for pets, and they are
likely to panic or even run away to try and escape the storm. If someone is struck by lightning, call 911 immediately.
Click here for additional lightning safety information.
Fire Weather Watch Issued when the combination of dry fuels and weather conditions supporting extreme fire danger and/or fire behavior is expected within 12 to 72 hours.
Red Flag Warning Issued when the combination of dry fuels and weather conditions supporting extreme fire danger and/or fire behavior is imminent or occurring.
Weather plays a key role in the growth and vitality of wildfires across the southwest. Persistent drought conditions and summertime heat waves significantly dry and prime forests for severe wildfires. Shrubs, grasses, and tress become the dry fuels needed to stoke a wildfire once it starts. A long duration of very low relative humidities and gusty winds can lead to rapid fire growth and dangerous conditions for firefighters and the general public in the path of a fast moving wildfire.
As the monsoon arrives an increased threat of lightning comes with it. Lightning, accompanied by little rainfall, start many wildfires each year. However, humans are the number one cause of wildfires due to carelessness or intentional actions.
National Weather Service offices predict the weather conditions that may lead to the development and spread of wildfires. When critical fire weather criteria are expected to be met, the NWS coordinates with all federal, state, county, city and local fire and wildland agencies to plan ahead for potential wildfires.
Take action ahead of time by preparing your home against wildfires. Clear the brush at least 30 feet away from your home and time tree branches away from chimneys and electrical lines. Enclose roof eaves and undersides of decks with fire resistant materials. Develop a home evacuation place in case you need to leave in an emergency. Have two exit routes from your neighborhood, and listen to instructions from public officials. the greatest health threat from smoke generated by a wildfire is to those with heart and lung conditions, especially older adults and children.
Tornado Warning A tornado has been sited and is still on the ground, or is about to develop
based on radar information. Take cover now!
Tornadoes do occur in Arizona. Unfortunately, many of them here are not detectible by radar because they are either too small,
hidden by interfering mountains, or develop from the ground up. While they do not last long, they can occur with little or no
warning, and can do considerable damage. If you see a tornado, which stretches from the clouds all the way down to the surface,
take the same precautions you would for a severe thunderstorm. Move inside a strong building away from windows. A small, central,
interior room like a bathroom is best. If caught outside or in a vehicle, lie flat in a nearby ditch or depression. Mobile homes,
even if tied down, offer little protection from tornadoes, and should be abandoned.