Public Health
Drought can cause significant human health outcomes that can challenge public health departments, emergency managers, and healthcare providers. Drought can lead to decreased water quantity and quality, increased incidence of illness or disease, increased mortality rates, and adverse mental health outcomes as livelihoods are challenged.
This map shows current National Weather Service Heat Advisories, Excessive Heat Watches, and Excessive Heat Warnings for counties across the U.S.
- Heat Advisories and Excessive Heat Warnings are issued within 12 hours of the onset of extremely dangerous heat conditions, based on the maximum heat index (typically >100°F or >105°F, respectively, but this varies by location).
- Excessive Heat Watches are issued when conditions are favorable for an excessive heat event in the next 24 to 72 hours, but its occurrence and timing is still uncertain.
Learn more about these warnings on Weather.gov.
A hazardous heat risk area typically indicates a 40% or greater chance of exceeding NWS Heat Advisory criteria, based on the Heat Index for your location, or widespread major (level 3) or scattered extreme (level 4) HeatRisk.
The U.S. Air Quality Index (AQI) is designed to communicate whether air quality is healthy or unhealthy. This map displays the AQI at sensors across the U.S. alongside the current U.S. Drought Monitor, as of 10 a.m. Eastern.
This map shows the Center for Disease Control and Prevention's 2018 Social Vulnerability Index (SVI) designations alongside current drought conditions from the U.S. Drought Monitor. The SVI uses 15 U.S. census variables at tract level (e.g., poverty, lack of vehicle access, crowded housing) to help local officials identify communities that may need support in preparing for or recovering from hazards, like drought.
Air temperature can have wide-ranging effects on natural processes. Warmer air temperatures increase evapotranspiration—which is the combination of evaporation from the soil and bodies of water and transpiration from plants—and lower soil moisture.
Learn MoreExtreme weather events can interact or cascade—where one disaster event triggers or changes the probability of another event. For example, drought conditions can increase the probability of large-scale wildfires, and droughts are often accompanied by extreme heat. By including drought in multi-hazard planning, a community can consolidate its resources and develop coordinated responses before a disaster.
Learn MoreDrought can cause significant human health outcomes that can challenge public health departments, emergency managers, and healthcare providers. Drought can lead to decreased water quantity and quality, increased incidence of illness or disease, increased mortality rates, and adverse mental health outcomes as livelihoods are challenged.
Learn MoreAir temperature can have wide-ranging effects on natural processes. Warmer air temperatures increase evapotranspiration—which is the combination of evaporation from the soil and bodies of water and transpiration from plants—and lower soil moisture.
Learn MoreFlash drought is the rapid onset or intensification of drought. Unlike slow-evolving drought, which is caused by a decline in precipitation, flash drought occurs when low precipitation is accompanied by abnormally high temperatures, high winds, and/or changes in radiation. These sometimes-rapid changes can quickly raise evapotranspiration rates and remove available water from the landscape.
Learn MoreDrought can reduce the water availability and water quality necessary for productive farms, ranches, and grazing lands, resulting in significant negative direct and indirect economic impacts to the agricultural sector. Monitoring agricultural drought typically focuses on examining levels of precipitation, evaporative demand, soil moisture, and surface/groundwater quantity and quality.
Learn MoreExtreme weather events can interact or cascade—where one disaster event triggers or changes the probability of another event. For example, drought conditions can increase the probability of large-scale wildfires, and droughts are often accompanied by extreme heat. By including drought in multi-hazard planning, a community can consolidate its resources and develop coordinated responses before a disaster.
Learn MoreDrought can cause significant human health outcomes that can challenge public health departments, emergency managers, and healthcare providers. Drought can lead to decreased water quantity and quality, increased incidence of illness or disease, increased mortality rates, and adverse mental health outcomes as livelihoods are challenged.
Learn MoreDuring drought conditions, fuels for wildfire, such as grasses and trees, can dry out and become more flammable. Drought can also increase the probability of ignition and the rate at which fire spreads. Temperature, soil moisture, humidity, wind speed, and fuel availability (vegetation) are all factors that interact to influence the frequency of large wildfires.
Learn MoreExtreme weather events can interact or cascade—where one disaster event triggers or changes the probability of another event. For example, drought conditions can increase the probability of large-scale wildfires, and droughts are often accompanied by extreme heat. By including drought in multi-hazard planning, a community can consolidate its resources and develop coordinated responses before a disaster.
Learn MoreDrought can cause significant human health outcomes that can challenge public health departments, emergency managers, and healthcare providers. Drought can lead to decreased water quantity and quality, increased incidence of illness or disease, increased mortality rates, and adverse mental health outcomes as livelihoods are challenged.
Learn MoreNational Weather Service Heat Warnings
Excessive Heat Watch
Heat Watches are issued when conditions are favorable for an excessive heat event in the next 24 to 72 hours. A Watch is used when the risk of a heat wave has increased, but its occurrence and timing is still uncertain. Learn more from the National Weather Service.
Heat Advisory
A Heat Advisory is issued within 12 hours of the onset of extremely dangerous heat conditions. The general rule is when the maximum heat index temperature is expected to be 100°F or higher for at least 2 days, and nighttime air temperatures will not drop below 75°F. However, these criteria vary across the country, especially for areas that are not used to dangerous heat conditions. Learn more from the National Weather Service.
Excessive Heat Warning
An Excessive Heat Warning is issued within 12 hours of the onset of extremely dangerous heat conditions. The general rule is when the maximum heat index temperature is expected to be 105°F or higher for at least 2 days, and nighttime air temperatures will not drop below 75°F. However, these criteria vary across the country, especially for areas not used to extreme heat conditions. Learn more from the National Weather Service.
Hazard Outlook for Days 3–7
Risk of Hazardous Heat
This area has a risk for hazardous heat 3 days from now through 7 days from now. This typically means that National Weather Service forecasters predict a 40% or greater chance of exceeding widespread NWS Heat Advisory criteria, based on the Heat Index for your location. Or, for the West, widespread major (level 3) or scattered extreme (level 4) HeatRisk is present.
Air Quality
AQI 0 to 50: Good
Air quality is satisfactory, and air pollution poses little or no risk. Learn more.
AQI 51 to 100: Moderate
Air quality is acceptable. However, there may be a risk for some people, particularly those who are unusually sensitive to air pollution. Learn more.
AQI 101 to 150: Unhealthy for Sensitive Groups
Members of sensitive groups may experience health effects. The general public is less likely to be affected. Learn more.
AQI 151 to 200: Unhealthy
Some members of the general public may experience health effects; members of sensitive groups may experience more serious health effects. Learn more.
AQI 201 to 300: Very Unhealthy
Health alert: The risk of health effects is increased for everyone. Learn more.
AQI >301: Hazardous
Health warning of emergency conditions: everyone is more likely to be affected. Learn more.
U.S. Drought Monitor
D0 - Abnormally Dry
Abnormally Dry (D0) indicates a region that is going into or coming out of drought, according to the U.S. Drought Monitor. View typical impacts by state.
D1 – Moderate Drought
Moderate Drought (D1) is the first of four drought categories (D1–D4), according to the U.S. Drought Monitor. View typical impacts by state.
D2 – Severe Drought
Severe Drought (D2) is the second of four drought categories (D1–D4), according to the U.S. Drought Monitor. View typical impacts by state.
D3 – Extreme Drought
Extreme Drought (D3) is the third of four drought categories (D1–D4), according to the U.S. Drought Monitor. View typical impacts by state.
D4 – Exceptional Drought
Exceptional Drought (D4) is the most intense drought category, according to the U.S. Drought Monitor. View typical impacts by state.
Social Vulnerability Index (SVI)
U.S. Drought Monitor
D0 - Abnormally Dry
Abnormally Dry (D0) indicates a region that is going into or coming out of drought, according to the U.S. Drought Monitor. View typical impacts by state.
D1 – Moderate Drought
Moderate Drought (D1) is the first of four drought categories (D1–D4), according to the U.S. Drought Monitor. View typical impacts by state.
D2 – Severe Drought
Severe Drought (D2) is the second of four drought categories (D1–D4), according to the U.S. Drought Monitor. View typical impacts by state.
D3 – Extreme Drought
Extreme Drought (D3) is the third of four drought categories (D1–D4), according to the U.S. Drought Monitor. View typical impacts by state.
D4 – Exceptional Drought
Exceptional Drought (D4) is the most intense drought category, according to the U.S. Drought Monitor. View typical impacts by state.
This map shows current National Weather Service Heat Advisories, Excessive Heat Watches, and Excessive Heat Warnings for counties across the U.S.
- Heat Advisories and Excessive Heat Warnings are issued within 12 hours of the onset of extremely dangerous heat conditions, based on the maximum heat index (typically >100°F or >105°F, respectively, but this varies by location).
- Excessive Heat Watches are issued when conditions are favorable for an excessive heat event in the next 24 to 72 hours, but its occurrence and timing is still uncertain.
Learn more about these warnings on Weather.gov.
A hazardous heat risk area typically indicates a 40% or greater chance of exceeding NWS Heat Advisory criteria, based on the Heat Index for your location, or widespread major (level 3) or scattered extreme (level 4) HeatRisk.
The U.S. Air Quality Index (AQI) is designed to communicate whether air quality is healthy or unhealthy. This map displays the AQI at sensors across the U.S. alongside the current U.S. Drought Monitor, as of 10 a.m. Eastern.
This map shows the Center for Disease Control and Prevention's 2018 Social Vulnerability Index (SVI) designations alongside current drought conditions from the U.S. Drought Monitor. The SVI uses 15 U.S. census variables at tract level (e.g., poverty, lack of vehicle access, crowded housing) to help local officials identify communities that may need support in preparing for or recovering from hazards, like drought.
This map is updated daily on Drought.gov. To see the latest heat advisories, watches, and warnings from the National Weather Service, visit Weather.gov.
The National Weather Service's Weather Prediction Center issues the Day 3–7 Hazards Outlook daily Monday–Friday by 3:30 p.m. EST/4:30 p.m. EDT. This map is updated on Drought.gov around 7 p.m. ET Monday–Friday.
On Drought.gov, Air Quality Index maps are updated daily at 10 a.m. Eastern. View hourly air quality information from AirNow.
CDC's Social Vulnerability Index data are from 2018. The U.S. Drought Monitor map is updated weekly on Thursday mornings, with data valid through that Tuesday at 7 am Eastern.
Air temperature can have wide-ranging effects on natural processes. Warmer air temperatures increase evapotranspiration—which is the combination of evaporation from the soil and bodies of water and transpiration from plants—and lower soil moisture.
Learn MoreExtreme weather events can interact or cascade—where one disaster event triggers or changes the probability of another event. For example, drought conditions can increase the probability of large-scale wildfires, and droughts are often accompanied by extreme heat. By including drought in multi-hazard planning, a community can consolidate its resources and develop coordinated responses before a disaster.
Learn MoreDrought can cause significant human health outcomes that can challenge public health departments, emergency managers, and healthcare providers. Drought can lead to decreased water quantity and quality, increased incidence of illness or disease, increased mortality rates, and adverse mental health outcomes as livelihoods are challenged.
Learn MoreAir temperature can have wide-ranging effects on natural processes. Warmer air temperatures increase evapotranspiration—which is the combination of evaporation from the soil and bodies of water and transpiration from plants—and lower soil moisture.
Learn MoreFlash drought is the rapid onset or intensification of drought. Unlike slow-evolving drought, which is caused by a decline in precipitation, flash drought occurs when low precipitation is accompanied by abnormally high temperatures, high winds, and/or changes in radiation. These sometimes-rapid changes can quickly raise evapotranspiration rates and remove available water from the landscape.
Learn MoreDrought can reduce the water availability and water quality necessary for productive farms, ranches, and grazing lands, resulting in significant negative direct and indirect economic impacts to the agricultural sector. Monitoring agricultural drought typically focuses on examining levels of precipitation, evaporative demand, soil moisture, and surface/groundwater quantity and quality.
Learn MoreExtreme weather events can interact or cascade—where one disaster event triggers or changes the probability of another event. For example, drought conditions can increase the probability of large-scale wildfires, and droughts are often accompanied by extreme heat. By including drought in multi-hazard planning, a community can consolidate its resources and develop coordinated responses before a disaster.
Learn MoreDrought can cause significant human health outcomes that can challenge public health departments, emergency managers, and healthcare providers. Drought can lead to decreased water quantity and quality, increased incidence of illness or disease, increased mortality rates, and adverse mental health outcomes as livelihoods are challenged.
Learn MoreDuring drought conditions, fuels for wildfire, such as grasses and trees, can dry out and become more flammable. Drought can also increase the probability of ignition and the rate at which fire spreads. Temperature, soil moisture, humidity, wind speed, and fuel availability (vegetation) are all factors that interact to influence the frequency of large wildfires.
Learn MoreExtreme weather events can interact or cascade—where one disaster event triggers or changes the probability of another event. For example, drought conditions can increase the probability of large-scale wildfires, and droughts are often accompanied by extreme heat. By including drought in multi-hazard planning, a community can consolidate its resources and develop coordinated responses before a disaster.
Learn MoreDrought can cause significant human health outcomes that can challenge public health departments, emergency managers, and healthcare providers. Drought can lead to decreased water quantity and quality, increased incidence of illness or disease, increased mortality rates, and adverse mental health outcomes as livelihoods are challenged.
Learn MoreWater Quality and Quantity
Drought can reduce the water supply that serves not only households and businesses, but also at-risk populations. Droughts can also lead to compromised water quality due to factors like increased salinity, increased algal production, less dilution, and reduced oxygen levels in the water system.
Air Quality
During drought, there is an increased risk for wildfires and dust storms. Particulate matter from these events can irritate bronchial passages and lungs and exacerbate chronic heart and lung conditions.
Increased Incidence of Illness and Disease
Drought often results in drier conditions, which can increase the risk of disease. For example, drier conditions can increase reproduction of a fungus found in soils and lead to the disease coccidioidomycosis, or Valley fever.
Mental Health Impacts
Drought and its economic consequences can lead to increased mental health impacts, including mood disorders, substance abuse, domestic violence, and suicide.
Drought Impacts on Public Health
Drought’s slow rise can result in both short- and long-term health consequences.
Human health implications of drought include:
- Compromised quantity and quality of drinking water
- Effects on air quality
- Diminished living conditions related to energy, air quality, and sanitation and hygiene
- Compromised food and nutrition
- Increased incidence of illness and disease, including anxiety, depression, or other adverse mental health outcomes
- Increased recreational risks.
Drought can affect the health of communities in different ways, depending on factors such as the structure and capacity of existing water systems, local governance of water use, economic development, the at-risk populations living within the affected area, and other societal elements, such as the presence of local social networks. Better understanding the linkages between drought events, related impacts, and consequences for human health can help public health agencies and emergency managers prepare for drought-associated health impacts and save lives.
Several resources are available to assess the public health needs in a community related to drought events. During California’s significant drought from 2012–2016, Mariposa and Tulare Counties, in cooperation with CDC, completed the first Community Assessment for Public Health Emergency Response (CASPER) reports on drought. The purpose of the CASPER reports was to assess the perceptions of the drought and of water use, learn how households coped with dry wells, identify ways households are conserving water, determine where and how households are seeking assistance, establish whether the drought caused any mental health effects or exacerbations of chronic diseases, and assess disaster communication issues. CASPER drought studies have also been completed in Oregon. Learn more.
In 2019, NIDIS helped to convene a National Drought and Public Health Summit to bring together a diverse set of local, state, federal, tribal, nonprofit, and academic stakeholders for a discussion around the linkages between droughts and human health. Participants discussed ways to properly prepare our nation’s public health agencies and organizations for the health hazards associated with drought, and identified how various partners and stakeholders can incorporate public health impacts into drought and climate tools. Regionally-focused drought and health workshops, along with a report iterating action items to further understand the relationship between drought and public health, were among the next steps agreed upon following the Summit.
Drought Early Warning for the Public Health Sector
Drought can have far-reaching impacts on public health, including decreased water quality and quantity, increased incidence of illness and disease, increased mortality rates, and adverse mental health outcomes as livelihoods are challenged. Drought early warning is essential to ensure health professionals and emergency managers are prepared to help communities mitigate the impacts of a drought event. The resources below are organized by the key components of a drought early warning system: (1) drought observation and monitoring; (2) drought planning and preparedness; (3) prediction and forecasting of drought; (4) communication and outreach to the public and affected sectors; and (5) interdisciplinary and applied research on topics of concern to drought-affected sectors.
Planning & Preparedness
Communication & Outreach
Interdisciplinary Research & Applications
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