Longmont, CO Flood Zone Map
Last updated: August 2026
Longmont faces severe flood risk from St. Vrain Creek, which devastated the city during the 2013 Colorado floods when record rainfall caused catastrophic damage along the Front Range. The city holds a CRS Class 5 rating, providing residents a 25% flood insurance discount.
Boulder County has recorded 1,784 NFIP flood insurance claims since 1978, totaling $49.6M in payouts. Explore the full NFIP claims data by state and county to see how this area compares nationally.
FEMA Region
Region 8
NFIP Policies
4,961
Boulder County
Avg. Premium
$819/yr
Boulder County
NFIP Flood Insurance Claims: Boulder County
Properties in Boulder County have filed 1,784 NFIP flood insurance claims totaling $49.6M in payouts since 1978. The average claim payout is $28K.
Highest-Claim Years
2013
1,520 claims - $48.4M
1995
53 claims - $50K
2022
17 claims - $112K
Claims by Flood Zone
Source: OpenFEMA NFIP Claims API. Data sourced August 2026. See national claims data.
Flood Insurance Coverage: Boulder County
Only roughly 1 in 26 households in Boulder County carries NFIP flood insurance (4% of estimated households). With 36 recorded flood events and $298.3M in damage, most flood losses in this county are likely uninsured.
Penetration Rate
4%
roughly 1 in 26 households
Historical Claims Ratio
1 in 3
1,784 claims over 45+ years across 4,961 current policies
Avg. Claim Payout
$27,794
Per claim, county-wide since 1978
Historically, Boulder County has averaged 1 claim for every 3 active policies (since 1978). This compares cumulative claims against today's policy count and does not predict future claim likelihood.
Coverage data: NFIP policies as of August 2026, claims since 1978 (August 2026), population from FEMA NRI. All figures are county-wide and include Longmont.
Not sure whether you're required to carry it? See do I need flood insurance?, or compare NFIP vs. private flood insurance.
Repetitive Loss Properties: Boulder County
Boulder County has 18 properties with multiple flood insurance losses, including 0 severe repetitive loss properties. Severe repetitive loss is a subset of multiple loss, not a separate count. Data sourced August 2026.
Multiple Loss
18
2+ claims within 10 years
Severe Repetitive Loss
0
4+ claims or 2 exceeding value
Mitigated
0
Received FEMA mitigation
By Flood Zone
Source: OpenFEMA NFIP Multiple Loss Properties. Data sourced August 2026.
Flood Insurance Discount: Longmont
Longmont participates in FEMA's Community Rating System (CRS), a voluntary program that rewards communities for flood mitigation efforts beyond minimum NFIP requirements. Residents in the Special Flood Hazard Area may qualify for reduced flood insurance premiums.
CRS Class
Class 5
SFHA Premium Discount
25% off
CRS classes range from 1 (best) to 10 (no discount). Longmont's Class 5 rating means NFIP policyholders in the SFHA can receive up to a 25% discount on their flood insurance premiums. Properties outside the SFHA may receive a 10% discount.
Source: FEMA Community Rating System, April 2026. Discounts apply to NFIP policies only.
Federal Flood Disaster History: Boulder County
Boulder County has been included in 6 federal flood-related disaster declarations.
...and 1 earlier declaration since 1969.
These declarations affected communities across Boulder County, including Longmont.
Source: OpenFEMA Disaster Declarations Summaries API. Data sourced August 2026.
Recorded Flood Events: Boulder County
NOAA has recorded 36 flood events in Boulder County since 1996, causing $298.3M in damage and 4 deaths.
Costliest Events
Events by Type
Source: NOAA Storm Events Database, 1996-2026. Data sourced August 2026.
Flood Mitigation: Boulder County
FEMA has funded mitigation for 132 properties in Boulder County, investing $17.5M in flood risk reduction. Common mitigation actions include acquisition (buying and demolishing flood-prone structures), elevation (raising buildings above flood level), and safe rooms (wind/storm shelters for tornado and hurricane protection).
By Action Type
Source: OpenFEMA Hazard Mitigation Assistance. Data sourced August 2026. FEMA records a total payment per grant rather than per property, so the dollar figure is an estimate that splits each grant across the properties it covers; the property count is exact.
FEMA Flood Risk Profile: Boulder County
Based on FEMA's National Risk Index, which evaluates flood risk at the county level using historical loss data, exposure, and vulnerability.
Inland Flood Risk
Relatively ModerateEst. annual loss: $69.1M
Source: FEMA National Risk Index, county-level assessment. Individual property risk may vary.
What Your Flood Zone Means in Longmont
Longmont faces multiple inland flood threats, including riverine flooding from nearby waterways and flash flooding from intense rainfall overwhelming urban drainage systems. Properties near river corridors face the highest risk, but stormwater backup can affect neighborhoods well outside the mapped floodplain. The most common FEMA flood zone designations in Longmont are Zone AE, Zone AO, Zone X. FEMA's National Risk Index estimates the county's annual expected loss from inland flooding at over $69.1M. Longmont has Zone AO areas subject to sheet-flow flooding, where shallow water spreads across broad, flat terrain rather than channeling through waterways.
With both riverine and urban stormwater flood risk, insurance costs in Longmont depend heavily on a property's elevation relative to nearby waterways and the local drainage infrastructure. FEMA's Risk Rating 2.0 prices in multiple inland flood sources rather than relying on the flood zone line alone. If your property is in a Special Flood Hazard Area (SFHA) and you have a federally regulated or government-backed mortgage, federal law generally requires your lender to ensure you carry flood insurance.
Flood zone boundaries in Longmont can shift when FEMA updates its Flood Insurance Studies or when upstream development changes how water moves through the watershed. New stormwater infrastructure or dam modifications can also trigger map revisions. Use our free lookup tool to check the current flood zone for any Longmont address.
Longmont, CO Flood Zone FAQ
What flood zones are in Longmont, CO?
The most common FEMA flood zones in Longmont are Zone AE, Zone AO, Zone X. Properties in these high-risk zones (SFHA) may require flood insurance with a federally regulated or government-backed mortgage.
Is flood insurance required in Longmont?
If your Longmont property is in a Special Flood Hazard Area (SFHA) and you have a federally regulated or government-backed mortgage, federal law generally requires your lender to ensure you carry flood insurance. Properties in Zone X are not federally required to carry flood insurance, though coverage is still recommended since about a quarter of all NFIP flood claims come from properties outside high-risk zones.
How do I check my flood zone in Longmont?
Enter your Longmont address in the search tool above for an instant flood zone determination. Results include your FEMA flood zone, SFHA status, base flood elevation (if available), and FIRM panel information, pulled directly from FEMA's National Flood Hazard Layer.
Does Longmont offer flood insurance discounts?
Yes. Longmont participates in FEMA's Community Rating System (CRS) with a Class 5 rating, qualifying residents in the Special Flood Hazard Area for up to a 25% discount on NFIP flood insurance premiums. Properties outside the SFHA may receive a 10% discount.
Has Longmont experienced major flooding events?
Boulder County, where Longmont is located, has been part of 6 federal disaster declarations for flooding, hurricanes, or severe storms. The most recent was Severe Storms, Tornadoes, Flooding, Landslides, and Mudslides in 2015. Federal disaster declarations are issued when flooding overwhelms local resources and triggers FEMA assistance programs.
How many flood insurance claims have been filed in Longmont?
Boulder County has recorded 1,784 NFIP flood insurance claims totaling $49.6M in payouts since 1978. The year with the most claims was 2013, with 1,520 claims and $48.4M in payouts. These figures cover all NFIP claims in the county, including Longmont.
How many flood insurance policies are there in Longmont?
Boulder County had 4,961 NFIP flood insurance policies written or renewed over the trailing 13 months, with an average annual premium of $819. The most policies are in Zone AE (2,690 policies). These are county-level counts of policies written or renewed in the trailing 13 months, not a point-in-time count of policies in force - a policy renewed inside that window is counted twice.
How many Longmont properties have flooded repeatedly?
Boulder County has 18 properties with multiple flood losses on record, including 0 severe repetitive loss properties. These are properties that have experienced four or more NFIP claims of $5,000+ or two claims exceeding the building value.
Can my Longmont property be removed from a high-risk flood zone?
Yes, if your property's natural ground elevation is above the Base Flood Elevation and FEMA inadvertently mapped it in a high-risk zone, you can apply for a Letter of Map Amendment (LOMA). A successful LOMA removes the property from the Special Flood Hazard Area, generally eliminating the federal mandatory flood insurance requirement. You will need an elevation certificate from a licensed surveyor. If a property was raised above the BFE with fill material, the process is a LOMR-F rather than a LOMA.
What is Base Flood Elevation in Longmont?
Base Flood Elevation (BFE) is the predicted height of floodwaters during a 1% annual chance (100-year) flood, shown on FEMA maps as an elevation number in feet above sea level. In Longmont's Zone AE areas, BFE lines appear on the FIRM as wavy contours labeled with elevation values. Properties with a lowest floor at or above the BFE typically qualify for significantly lower NFIP flood insurance premiums.
Other Colorado Cities
Understanding Flood Zones
See the Flood Map for Any Longmont, CO Address
Enter a Longmont, CO address to view its FEMA flood map, zone designation, SFHA status, and insurance requirements.
Disclaimer: Flood risk data on this page is sourced from FEMA datasets including the National Risk Index, NFIP claims and policy records, disaster declarations, and the Community Rating System. These datasets were last extracted on August 2026 and may not reflect the most recent changes. Always verify current flood zone status through FEMA or a licensed determination provider before making property, insurance, or lending decisions.