Although the real estate market in Colorado has been on a tear for years, recent signs suggest that a cool-off may finally be on the way — including the increasing number of homes in various parts of the state that are underwater.

According to the folks at Attom Data, who've just released a new report about home equity during the third quarter of 2018, a home is considered to be seriously underwater when the combined balance of loans is at least 25 percent higher than the property's estimated market value.

In other words, the owners of the house owe a quarter more than it's worth.

Attom Data's figures show that more than 4.9 million properties in the United States qualified as seriously underwater during 2018's third quarter, representing 8.8 percent of all American properties with a mortgage. That's actually down from 9.3 percent in the second quarter of 2018 but slightly up from 8.7 percent in the third quarter of last year.

Included in the report is a heat map that allows users to discover the number and percentage of underwater properties in communities by zip code — and compared to many places in other parts of the country, including the so-called Rust Belt, Colorado's in comparatively good shape, as graphically depicted in a screen capture below. The five zip codes with the highest share of seriously underwater property range from 59.2 percent in one section of Cleveland, Ohio, to 71 percent in a portion of Trenton, New Jersey — but the largest percentage in Colorado is the 81611 zip in Aspen, at 19.4 percent.

However, the latter number is up considerably from this time last year, when 15.4 percent of properties in Aspen's 81611 zip code were seriously underwater, a previous Attom Data analysis shows. The same is true for the Colorado zip with the second-highest percentage, 81657 in Vail, which has gone from 11.3 percent of homes seriously underwater to 15 percent over the past twelve months.

At present, the problem is considerably less severe in Denver and along the Eastern Slope. But if the market's winds have finally shifted, that could change. And thousands of Colorado homes are seriously underwater right now.

Continue to count down thirty Colorado zip codes, ranked from those with the lowest to the highest percentages of seriously underwater properties. Note that "MSA" stands for "Metropolitan Statistical Area."

City: Denver

MSA: Denver-Aurora-Lakewood

Zip Code: 80227

Number Seriously Underwater: 187

Pct Seriously Underwater: 2.2%

Q3 2018 Total with Loans: 8,692

City: Longmont

MSA: Boulder

Zip Code: 80501

Number Seriously Underwater: 205

Pct Seriously Underwater: 2.4%

Q3 2018 Total with Loans: 8,411

City: Brighton

MSA: Denver-Aurora-Lakewood

Zip Code: 80601

Number Seriously Underwater: 212

Pct Seriously Underwater: 2.5%

Q3 2018 Total with Loans: 8,426

City: Parker

MSA: Denver-Aurora-Lakewood

Zip Code: 80134

Number Seriously Underwater: 531

Pct Seriously Underwater: 2.6%

Q3 2018 Total with Loans: 20,135

City: Peyton

MSA: Colorado Springs

Zip Code: 80831

Number Seriously Underwater: 218

Pct Seriously Underwater: 2.6%

Q3 2018 Total with Loans: 8,375

City: Breckenridge

MSA: Breckenridge

Zip Code: 80424

Number Seriously Underwater: 147

Pct Seriously Underwater: 2.7%

Q3 2018 Total with Loans: 5,347

City: Aurora

MSA: Denver-Aurora-Lakewood

Zip Code: 80016

Number Seriously Underwater: 454

Pct Seriously Underwater: 2.9%

Q3 2018 Total with Loans: 15,406

City: Arvada

MSA: Denver-Aurora-Lakewood

Zip Code: 80002

Number Seriously Underwater: 120

Pct Seriously Underwater: 2.9%

Q3 2018 Total with Loans: 4,101

City: Golden

MSA: Denver-Aurora-Lakewood

Zip Code: 80401

Number Seriously Underwater: 294

Pct Seriously Underwater: 3.0%

Q3 2018 Total with Loans: 9,917

City: Evergreen

MSA: Denver-Aurora-Lakewood

Zip Code: 80439

Number Seriously Underwater: 285

Pct Seriously Underwater: 3.4%

Q3 2018 Total with Loans: 8,302

City: Aurora

MSA: Denver-Aurora-Lakewood

Zip Code: 80010

Number Seriously Underwater: 239

Pct Seriously Underwater: 3.9%

Q3 2018 Total with Loans: 6,187

City: Aurora

MSA: Denver-Aurora-Lakewood

Zip Code: 80011

Number Seriously Underwater: 336

Pct Seriously Underwater: 4.0%

Q3 2018 Total with Loans: 8,445

City: Monument

MSA: Colorado Springs

Zip Code: 80132

Number Seriously Underwater: 300

Pct Seriously Underwater: 4.0%

Q3 2018 Total with Loans: 7,436

City: Castle Rock

MSA: Denver-Aurora-Lakewood

Zip Code: 80104

Number Seriously Underwater: 330

Pct Seriously Underwater: 4.1%

Q3 2018 Total with Loans: 7,980

City: Denver

MSA: Denver-Aurora-Lakewood

Zip Code: 80202

Number Seriously Underwater: 138

Pct Seriously Underwater: 4.3%

Q3 2018 Total with Loans: 3,177

City: Steamboat Springs

MSA: Steamboat Springs

Zip Code: 80487

Number Seriously Underwater: 261

Pct Seriously Underwater: 4.8%

Q3 2018 Total with Loans: 5,475

City: Boulder

MSA: Boulder

Zip Code: 80302

Number Seriously Underwater: 251

Pct Seriously Underwater: 5.4%

Q3 2018 Total with Loans: 4,622

City: Fort Morgan

MSA: Fort Morgan

Zip Code: 80701

Number Seriously Underwater: 153

Pct Seriously Underwater: 5.5%

Q3 2018 Total with Loans: 2,791

City: Denver

MSA: Denver-Aurora-Lakewood

Zip Code: 80203

Number Seriously Underwater: 230

Pct Seriously Underwater: 5.7%

Q3 2018 Total with Loans: 4,026

City: Montrose

MSA: Montrose

Zip Code: 81401

Number Seriously Underwater: 239

Pct Seriously Underwater: 5.8%

Q3 2018 Total with Loans: 4,102

City: Grand Junction

MSA: Grand Junction

Zip Code: 81501

Number Seriously Underwater: 300

Pct Seriously Underwater: 6.2%

Q3 2018 Total with Loans: 4,843

City: Glenwood Springs

MSA: Glenwood Springs

Zip Code: 81601

Number Seriously Underwater: 203

Pct Seriously Underwater: 6.4%

Q3 2018 Total with Loans: 3,191

City: Englewood

MSA: Denver-Aurora-Lakewood

Zip Code: 80113

Number Seriously Underwater: 371

Pct Seriously Underwater: 7.1%

Q3 2018 Total with Loans: 5,242

City: Estes Park

MSA: Fort Collins

Zip Code: 80517

Number Seriously Underwater: 288

Pct Seriously Underwater: 7.2%

Q3 2018 Total with Loans: 3,975

City: Sterling

MSA: Sterling

Zip Code: 80751

Number Seriously Underwater: 206

Pct Seriously Underwater: 7.8%

Q3 2018 Total with Loans: 2,643

City: Durango

MSA: Durango

Zip Code: 81301

Number Seriously Underwater: 808

Pct Seriously Underwater: 9.5%

Q3 2018 Total with Loans: 8,522

City: Avon

MSA: Edwards

Zip Code: 81620

Number Seriously Underwater: 289

Pct Seriously Underwater: 10.7%

Q3 2018 Total with Loans: 2,689

City: Pueblo

MSA: Pueblo

Zip Code: 81001

Number Seriously Underwater: 544

Pct Seriously Underwater: 11.1%

Q3 2018 Total with Loans: 4,905

City: Vail

MSA: Edwards

Zip Code: 81657

Number Seriously Underwater: 491

Pct Seriously Underwater: 15.0%

Q3 2018 Total with Loans: 3,266

City: Aspen

MSA: Glenwood Springs

Zip Code: 81611

Number Seriously Underwater: 656

Pct Seriously Underwater: 19.4%

Q3 2018 Total with Loans: 3,373