Fastest-Growing High-Risk Counties in Texas (2026): Montgomery #2, Fort Bend #9 in the U.S.

What RealtyHomes measured, which four Texas counties made the cut, and how the top 25 breaks down by state and hazard.

The RealtyHomes list ranks U.S. counties with at least 100,000 residents that FEMA's National Risk Index rates Relatively High or Very High for natural hazards, ordered by percentage population growth from July 2020 to July 2025. Texas placed four counties: Montgomery (#2, 24.9%), Collin (#5, 20.6%), Fort Bend (#9, 17.4%) and Denton (#11, 16.9%).

The 25 counties added about 2.07 million residents and 983,381 housing units in five years. Their median housing-stock growth was 16.8%, against 4.6% for other large counties. Florida placed 12 counties, Texas 4, North Carolina 3 and South Carolina 3, so four states account for 22 of the 25.

The hazard column is where the list gets useful for a Houston business. Of the 25 counties, 23 are rated Relatively High or Very High for lightning, 19 for hurricane, 16 for strong wind, 16 for tornado and 15 for inland flooding. Both Houston-area counties carry lightning as the top-rated hazard. Both Dallas-area counties carry tornado.

The table below compares the four Texas counties on the RealtyHomes list with Harris County, which sits in FEMA's highest risk tier and did not make the list, and adds one column RealtyHomes did not publish: net domestic migration for 2021 through 2025, which CinchOps computed from the Census Bureau's Vintage 2025 county file.

One basis note so the numbers can be checked. RealtyHomes measured growth from the July 1, 2020 population estimate, which is why Montgomery shows 155,825 residents added here and 160,643 on the CinchOps Houston Growth Index, which starts from the April 1, 2020 Census count. Both are correct. They start the clock at different points.

The study's central finding, read against the Census migration data for the three Houston-area counties that matter most to a local business.

RealtyHomes' own summary of the pattern is that "the strongest post-2020 growth is concentrated not in FEMA's absolute highest-risk counties, but in the next tier." In the Houston area that sentence has names. Harris County, in FEMA's highest tier, grew 6.6%. Montgomery County grew 24.9% and Fort Bend County grew 17.4%, directly across the county line.

The Census Bureau's county file shows how that happened. From 2021 through 2025, Harris County recorded net domestic migration of -157,010 people. Over the same five years Montgomery gained 116,575 net domestic movers and Fort Bend gained 79,829, a combined 196,404. Harris still grew, on international migration and births, but the households moving within the United States chose the two counties one tier out. Together, Montgomery and Fort Bend added 300,669 residents.

The tier line on FEMA's map did not hold in the last real test. Hurricane Beryl made landfall on July 8, 2024 as a Category 1 storm and, according to the Public Utility Commission of Texas investigation, knocked out service to about 2.2 million CenterPoint customers, roughly 90% of the utility's customer base. The IRS disaster relief that followed named 67 Texas counties, Harris, Fort Bend and Montgomery among them. The Supreme Court of Texas let justice courts in Fort Bend, Galveston, Harris, Matagorda and Montgomery counties extend civil deadlines, citing "difficulties with access, electricity, internet, travel, and communication."

For a 40-person engineering firm in Sugar Land or a CPA practice in The Woodlands, the practical reading is simple. Your county's growth outran the county FEMA worries about most, and your last outage was the same outage Harris had.

How each hazard on the RealtyHomes list reaches a small business through its IT, and why growth makes every one of them worse.

Lightning is the top-rated FEMA hazard for both Montgomery and Fort Bend counties in the RealtyHomes data, and lightning reaches a business through its electrical system: a surge or a brownout that hits the network switch, the server and the phone system long before any water does. In a county growing 17% to 25% in five years, the equipment taking that hit is usually sized for the company it used to be.

The pattern CinchOps sees most often on onboarding audits in Katy, Sugar Land and The Woodlands is a company that grew from 12 people to 50 without ever revisiting the closet. The battery backup bought for the 12-person era now carries twice the load and buys minutes rather than a clean shutdown. Surge protection stops at the power strip. The backup still runs to a drive on the shelf next to the server, in the same room, on the same circuit. Nothing failed yet, so nothing was changed.

Each hazard on the list has a different first failure. Lightning and strong wind trip power and cook electronics. A hurricane takes power and internet away for days across a wide area, which is what Beryl did to about 90% of CenterPoint's customers. Inland flooding takes the ground-floor rack and the backup drive sitting beside it. A tornado makes the building unreachable even when the gear inside survived. Growth does not change the list. It multiplies the blast radius, because every new hire is one more endpoint on the undersized battery and one more mailbox in a backup set nobody has restored from.

What fails first and what to protect first are different questions. Power fails first, but data is the one thing on the list a business cannot buy back, so the order of work starts there: immutable backup copies offsite and outside the Gulf Coast flood zone, verified rather than assumed. A cooked switch is replaced in a day. A lost client file is not. Then power: surge protection at the panel, a battery backup sized to the current headcount with automatic shutdown, and a generator plan if the business cannot close for a week. Then connectivity: a cellular failover path through SD-WAN and cloud phones that ring wherever staff end up. A business that does those three things in that order has handled lightning, Beryl and the flood in one pass.

CinchOps is a managed IT services provider based in Katy, Texas, serving small and mid-sized businesses across the Houston metro area. CinchOps specializes in cybersecurity, network security, managed IT support, VoIP, and SD-WAN for businesses with 10 to 200 employees.

Katy itself straddles Harris, Fort Bend and Waller counties, so the two Houston-area counties on the RealtyHomes list are the ground CinchOps works on every day. In 35+ years doing this, Shane Stevens has watched the same closet-sized problems scale up with every growth cycle in the Houston area, and the fix has not changed much: get the data, the power and the connection each onto a footing that does not depend on the building.

• Through business continuity and disaster recovery, backup copies are immutable, offsite and outside the Gulf Coast flood zone, and they cover servers, laptops, Microsoft 365 and Google Workspace.
• With managed IT support, battery backup sizing, surge protection and shutdown automation get reviewed as headcount changes instead of after the first outage, and the help desk answers in under 15 minutes.
• SD-WAN and VoIP mean the office keeps a cellular path to the internet and phones keep ringing on laptops and mobiles when the building goes dark.
• Cybersecurity with 24/7 threat monitoring means the days after a hurricane, when staff work from anywhere on whatever connection they can find, are covered as carefully as a normal Tuesday.
• CinchOps serves Katy, Sugar Land, Richmond, Fulshear and Missouri City in Fort Bend County, The Woodlands in Montgomery County, and Houston across Harris County.
• The industries that fill these counties, construction, engineering and CPA firms, each get a plan built around their own software and deadlines.

Montgomery and Fort Bend did not slow down for FEMA's map, and the businesses moving in with those 300,669 new residents will not either. The ones that stay open after the next Beryl will be the ones that treated a national high-risk ranking as a work order rather than a headline. If your closet still looks like the company you were five years ago, talk to CinchOps before the next lightning season does the audit for you.