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Overall Resilience Metrics

The climate in Fairfax County is becoming warmer, wetter, and weirder. Extreme heat, flooding, severe storms, and other changing hazards repeatedly impact our neighborhoods, infrastructure, services, and natural resources. The good news is that there is a lot we can do to adapt and boost our resilience to these conditions! Resilient Fairfax is Fairfax County’s climate adaptation and resilience plan and program.  Data and metrics help us track conditions and progress.

This page highlights general climate resilience data and metrics. For detailed information on the Resilient Fairfax plan and associated programs, please see the Resilient Fairfax page. For metrics on sectors such as community services or natural resources, please see the sector-specific pages linked at the bottom of this page.

three charts side by side showing the average temperature by yar, number of flash floods and numbers of thunderstorm wind events by year, showcasing the warmer wetter and weirder conditions in the county

The figure above summarizes the “warmer, wetter, weirder” conditions in Fairfax County in recent decades. For additional details on this data, please scroll down to the “warmer,” “wetter,” and “weirder” sections below.

Resilient Fairfax Map Viewer

Use the Resilient Fairfax Interactive Map Viewer interactive map to see various heat and flooding hazards, and how those hazards overlap with buildings, utilities, public services, natural resources, and more. The sections below walk through specific hazards.

This map will be updated as data becomes available. Please click this link to see a video explaining how to use this map.

Resilient Fairfax Strategies

The Resilient Fairfax Plan includes 48 strategies, organized into four pillars. The status of each strategy is summarized in the figure below. (Last updated April 2026).

For an ADA accessible version of this graphic, please email ResilientFairfax@fairfaxcounty.gov.

The status bars shown here are based on the number of implementation actions complete for each strategy. For example, if there are 5 implementation actions for a strategy, and 1 action is complete, the status bar is at 20%. Some actions are larger and/or more difficult than others. It is important to note that these status bars show how much work from the plan is completed; they do not show key outcomes of that work. For example, completing 50% of the plan’s implementation actions about “Green Infrastructure” does not mean that 50% of the county has adequate green infrastructure. To see progress on key outcomes, please see the “Key Metrics” section below. Additional information on the status of these strategies and actions can be found in the 2025 Climate Action Progress and Highlights Report. Please email ResilientFairfax@fairfaxcounty.gov with any questions.

Key Metrics

For an ADA accessible version of this graphic, please email ResilientFairfax@fairfaxcounty.gov.

Are we resilient to climate hazards? To answer that question, the county tracks dozens of climate resilience metrics, based on the Key Performance Indicators from the Resilient Fairfax plan.  A few key metrics are shown in the figure above.

In terms of flooding, people often think of floodplains, which are the strips of land next to rivers and streams. However, in Fairfax County we have urban flooding in addition to riverine (floodplain) flooding. In terms of floodplain (riverine) flooding, Fairfax County has reduced its risk by proactively protecting floodplains and limiting development. Few structures (0.9% of buildings) in Fairfax County are in floodplains, and nearly all of those (99%) are insurable buildings that have flood insurance, because it is a requirement for a federally backed mortgage. (Data is based on the 2010 FEMA FIRM). Outside of floodplains, however, urban flooding is an issue. Out of all buildings at risk of flooding in Fairfax County, approximately 28% are in floodplains, while the remaining 72% are vulnerable to potential urban flooding. (The data shown here is based on DPWES’ Analyzing Flood Risk Story Map.)

The county is addressing these flooding issues through a combination of policy updates, capital projects, and community services. In terms of community services, the Conservation Assistance Program continues its success, and the Flood Mitigation Assistance Program (FMAP) was launched in July 2024. FMAP has a goal of approximately 100 projects per year, which would mean approximately 500 projects by 2030. A total of 88 FMAP applications have been approved through 2025, or 17% of the 2030 milestone.

To adapt to increasing heat, the county provides Cooling Centers, cooling programs, tree planting, heat-resilient design, and more. Our Cooling Centers provide good coverage of the county. Specifically, 84% of our heat-vulnerable areas have a Cooling Center within 1 mile*. In terms of air conditioning access at home, progress has been accelerating. An estimated 2,460 households in Fairfax County need help with air conditioning equipment at home, based on a new analysis of Department of Tax Administration data on the HVAC status of homes. To date, 274 homes (11.1% of those in need) have received AC equipment installations, drop-offs, repairs, or replacements from the county’s cooling programs (Cooling Assistance, Senior Cool Care, and AC Rescue). The launch of AC Rescue in 2024, funded by Resilient Fairfax, helps to fill gaps that cannot be served by the other programs.

For storm resilience, there are also opportunities for enhanced resilience using back-up power sources. Of the 312 county government facilities on the county’s Continuity of Operations list, 17 facilities, or 5.5%, have generators.

*Using NASA satellite data, the county mapped the land surface temperatures across the county and then summarized those temperatures by Census Tract (Heat Exposure Index). Then, the county mapped populations that are more heat-sensitive, due to factors such as age, health conditions, poor housing conditions, and less ability to afford air conditioning (Heat Sensitivity Index). When these two maps are combined, we get the Heat Vulnerability Index. The Heat Vulnerability Index shows us that 69 of our Census Tracts have moderate-to-very high heat vulnerability. Of those 69 Census Tracts, 58 Census Tracts (or 84%) are within a 1-mile radius of a Cooling Center.

Warmer

Temperature Trends:

The interactive graphic below shows various temperature trends in Fairfax County.

Another way to visualize the warming trend is to chart years that were hotter or colder than average. The graph below shows how each year’s average annual temperature has compared to the norm. The “norm” is 54.26 degrees, based on the average of all temperatures in Fairfax County from 1962-2005. Years that were hotter than average are shown in red, above the baseline, and years colder than average are shown in blue, below the baseline. Of the last 20 years, 19 have been above average, demonstrating the warming Fairfax County is experiencing due to climate change.

Extreme Heat Days:

“Extreme heat” is defined by FEMA and CDC as “period of high heat and humidity with temperatures above 90F for at least 2-3 days.” High temperatures are especially dangerous when combined with humidity, which limits our ability to cool ourselves naturally by sweating.

In the past (1976-2005), Fairfax County averaged 25 days per year above 90°F. Today (1991-2020), that average has increased to 29 days per year.
By mid-century (2035-2064), Fairfax County is projected to have an average of 69 days per year above 90°F, and,
By the end of the century (2070-2099), 101 days per year, or approximately the whole summer, above 90°F.

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Urban Heat Island Effect:

average daytime summer land surface temperatures fairfax county virginia

While extreme heat affects all of us, it affects neighborhoods in “urban heat islands” more. Urban Heat Islands are areas of the county that remain hotter because they have more asphalt, densely-built buildings, roadways, and other infrastructure that retain heat. In contrast, rural areas with more green space and forests stay much cooler. This map shows the real daytime summer land surface temperatures, based on a multi-year average of the years 2013-2020 (Land surface temperatures are different from air temperatures). The areas in red have hotter land surface temperatures than the areas in blue. To see an interactive version of this map, please see the Resilient Fairfax Map Viewer. Fairfax County partnered with NASA DEVELOP to obtain these land surface satellite data. For more information on the satellite data, please see the NASA DEVELOP – Fairfax County Urban Heat Island Study. For detailed data on impacts of extreme heat, and specific populations and assets that are exposed to the Urban Heat Island effect, please see the Vulnerability and Risk Assessment. For information on what the county is doing to adapt and boost resilience to changing conditions including heat, please see the Resilient Fairfax Plan.

Wetter

Precipitation Intensity:

In Fairfax County, the intensity of precipitation has increased (i.e., it is raining harder than it used to). While the total amount of rain the county receives per year has been fairly consistent*, we are receiving this rain in heavier, shorter downpours and flash flood events. This intense rain causes flooding because our infrastructure and natural systems are not designed to handle such high volumes all at once. The Department of Public Works and Environmental Services (DPWES) is the primary agency responsible for stormwater management. For more information, please see Stormwater Management.

*The total quantity of precipitation received by the county per year has increased slightly. However, the bigger change is the increase in intensity of precipitation.

The figure below shows the number of flash flood events in Fairfax County between 1996 and 2025, as tracked by the National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Information Storm Events Database. There is wide variation in these events, but they are generally increasing in frequency over time.

We measure precipitation by intensity, duration, and frequency (or “IDF curves”). As can be seen in the chart below, using data from MARISA, the IDF curve for our area is shifting. The historic IDF curve is the lower line shown in red. The projected IDF curve is the higher line, shown in blue. This means that it is raining harder than it used to.

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Flooding Types:

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Fairfax County experiences a few different types of flooding. The map shown above, which is from the Resilient Fairfax Vulnerability and Risk Assessment, shows different types of flooding in Fairfax County.

Floodplain or riverine flooding occurs when water bodies overflow onto their banks. Approximately 2,215 buildings (or 0.9% of buildings) in Fairfax County are in FEMA Special Flood Hazard Area (“100 year”) floodplains. Floodplains in the map are shown in yellow.
Coastal flooding in Fairfax County refers to flooding of the Potomac River and associated tidal water bodies as a result of sea level rise, high tide, storm surge, or a combination thereof. Approximately 699 buildings (or 0.3% of buildings) are vulnerable to coastal flooding in Fairfax County. Coastal flooding in the map is shown in red. In this map, “SLR” refers to projected sea level rise of 1 foot and 3 feet, respectively. “Cat 1&2” and “Cat 3&4” refers to Category 1, 2, 3, and 4 storm surges that could push water onshore.
Urban or pluvial flooding occurs when heavy rain overwhelms stormwater management systems, pools in low-lying areas (sumps), cannot sink into the ground, or is blocked from reaching waterways (overland relief paths blocked). The exact number of structures vulnerable to urban flooding in Fairfax County varies by storm and type but is consistently higher than those vulnerable to floodplain flooding. As of 2021, over 97% of flooding-related service requests were not in floodplains. (See Resilient Fairfax Vulnerability and Risk Assessment). Potential urban flooding of various types is shown in the map and graph in blue.

Sea Level Rise and the Potomac River:

“Coastal flooding” in Fairfax County refers to flooding of the Potomac River and associated water bodies due to tidal flooding, sea level rise, coastal storm surge, or a combination of all three. Tides are measured with tide gauges. The nearest tide gauge is located in Washington DC. Since 1920, this area has already experienced an increase in sea level rise of 0.135 inches per year, or 13.56 inches over the past century. This water level is projected to increase by an additional 1 to 3.5 feet by 2050. There are approximately 699 buildings in Fairfax County that are vulnerable to this projected coastal flooding.

The figure below shows an example of a few neighborhoods that are especially vulnerable to flooding of the Potomac River (New Alexandria, Belle Haven, and Westgrove). From left to right, the images show existing conditions, additional projected sea level rise of 1 foot, additional projected sea level rise of 3 feet, and coastal storm surge (where the water goes if a severe tropical storm or hurricane pushes it on shore). These images are taken from the Resilient Fairfax Interactive Map Viewer.

Weirder

Storm Intensity and Frequency:

Storms are more frequent and intense than they used to be. The National Oceanic and Atmospheric Administration (NOAA) tracks the occurrence of storms and other significant weather phenomena “having sufficient intensity to cause loss of life, injuries, significant property damage, and/or disruption to commerce.” NOAA’s data for Fairfax County shows that we have seen an increase in the number of storm events per year and the number of days per year with storm events and storm-related property damage. (Please Power BI visual below). NOAA’s database goes back to the 1950s; however, methodology for tracking storm data changed in 1996 to include more storm types. Therefore, to avoid blending the increase in storm events with the increase in types of storms that are tracked, only data with consistent methodology are shown here (1996 and beyond).

One of the storm types that has been continuously tracked since the 1950s is “thunderstorm wind.” As can be seen in the chart below, in Fairfax County, the number of days per year with “thunderstorm wind” events severe enough to be tracked by NOAA has increased notably between 1950 and 2022. While much of this increase is due to a change in the storm events themselves, it is possible that a portion of this increase is due to improvements in storm tracking and reporting. For questions about the raw data, please contact NOAA.

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Department Resources

Related Resources

Overall Resilience Metrics

Resilient Fairfax Map Viewer

Resilient Fairfax Strategies

Key Metrics

Warmer

Temperature Trends:

Extreme Heat Days:

Urban Heat Island Effect:

Wetter

Precipitation Intensity:

Flooding Types:

Sea Level Rise and the Potomac River:

Weirder

Storm Intensity and Frequency:

Sector-Specific Metrics

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