Reading the numbers

So far, yes, across nearly 20 years of Charleston history. In full detail for 14 towns since 2016, towns scoring 60 to 80 typically gained about 6% in value a year later, and towns under 40 were about flat. Rebuilt for the whole market back to 2007, it turned cold three months before the 2007 price peak and warm about six months before the 2012 bottom. Run unchanged on five cities it was never built on, including Austin through its 27% drop, it lined up the same way.

The Cape Island Point Tide Gauge™, our market conditions score, rates how hot or cool each town's market is compared with that town's own history, from 0 to 100. 50 means normal for that town. It is built to show which way a market is leaning. The name comes from the instrument: a tide gauge measures the water rising and falling against a fixed mark, and this measures each market rising and falling against its own normal. It has been checked against nearly 20 years of Charleston history: in full detail for 14 towns since 2016, and rebuilt for the whole market back to 2007.

In detail, 2016 to 2025

The score was checked against Zillow home values in 14 Charleston-area towns from 2016 to 2025. Each month's score was compared with what that town's home values did over the next year:

The score usually changed direction three to six months before prices did. Its signal is strongest over the next 6 to 18 months and fades after about two years in normal times. In the 2007 downturn, its early warning held for three years.

The 2007 downturn and recovery, 2007 to 2016

The Tide Gauge itself only goes back to 2016, so it has not been through a real housing downturn. To see how it would have done, it was rebuilt for the whole local MLS from the MLS's own monthly reports, using the same method and three of its five measures (the other two were not published then). Prices in the area peaked in April 2007 and fell about 27% by January 2012.

It hit the bottom of the scale three months before prices peaked, while values were still rising, and it was back above 70 about six months before prices bottomed. It also missed: from mid-2009 to early 2011 it read about normal while prices kept falling. The reason is how it works. It compares each market with its own past, and after two years of slump the past it was comparing against was the slump itself. Homes for sale stayed above 11 months' worth that whole time. That is why the site now shows months of supply on a fixed scale right beside the score.

Other caveats: the 2004 to 2009 figures were read from charts in a 2012 report, so they are approximate, and in early 2007 the only past to compare with was the 2004 to 2006 boom.

A national version built from the same kind of supply measure also turned cool about a year before national home prices peaked in 2007.

Tested on five cities it was never built on

To check that it isn't just fitted to Charleston, the same math, unchanged, was run on five cities that boomed and then fell after 2022: Austin, Tampa, Phoenix, Boise and Cape Coral. Across 570 monthly readings since 2016, the results lined up with Charleston's: readings under 20 were followed by lower home values a year later 9 times in 10 (typically about −5%), and readings of 80 and up by gains of about 16%. In Austin, the score slid from 93 in January 2022 to 56 in May while values were still rising, hit 0 by December, and stayed in single digits for two years as values fell about 27%. It also missed there: in March 2022 it still read 78, and values fell 7% over the next year.

What it can't tell you

• It shows direction, not size. A cool score does not say how far prices might fall.
• In a long slump its sense of normal sinks with the market, so it can read about normal while prices are still falling. Check the months of supply shown beside it.
• It has one local downturn, one national one and five outside cities behind it. That is encouraging, not proof.
• Small towns with few sales can swing from month to month.
• It describes today's market. It is not a prediction, and it is not advice about any one person's decision.

Keeping score

Starting with August 2026, every month's published scores are saved as they were first shown and never revised. Each month, a year later, they will be checked against what home values actually did.

Yes, with credit and a link to capeislandpoint.com.

Yes. Anyone, including real estate agents, lenders, reporters and neighbors, is welcome to share charts, Tide Gauge readings and short quotes from this site, on social media, in newsletters, in presentations or with clients. Two simple rules:

• Give credit and a link. Use: Source: Cape Island Point Tide Gauge™, capeislandpoint.com (or Source: Cape Island Point Research for other charts). Keep the credit that is already on a chart or share picture.
• Keep it accurate. Don't change the numbers, crop a chart in a way that changes what it shows, or present a reading as more current than it is. Mention the month it covers.

Please don't:

• Republish a whole market note, Beacon piece or email. Quote a few sentences and link to the rest.
• Suggest that Cape Island Point endorses you, your listings or your services. The site is independent and isn't affiliated with any agent, brokerage, builder or lender.
• Copy the data in bulk, or sell or repackage it. The figures behind the site come from Zillow, Redfin, the local MLS (CTAR), Freddie Mac, the Census Bureau and others, each under its own terms; see Sources.

For anything beyond that, such as a regular data feature or a custom report, email brandon@capeislandpoint.com.

They measure different things: Zillow estimates what a typical home is worth, while Redfin and the MLS report what homes actually sold for, over different areas and time windows.

They measure different things, and four differences usually explain the gap:

• What is measured. Zillow's Home Value Index estimates what a typical home is worth, sold or not. Redfin and the MLS (CTAR) report the median price of homes that actually sold.
• Where. Redfin and Zillow use town limits. CTAR uses its own MLS market areas, which ignore town lines. CTAR's James Island area covers the whole island, including City of Charleston neighborhoods like Riverland Terrace; the Town of James Island is a smaller, less expensive slice.
• Which homes. CTAR splits single-family houses from townhouses and condos. Redfin town figures mix all home types, and condos pull the median down.
• When. CTAR reports one month. Redfin uses a 3-month rolling window. Zillow is smoothed over time. One month with a few big waterfront sales can jump $100,000 or more.

Example, August 2026: CTAR's James Island single-family median was $800,000 (42 sales, whole island, one month). Redfin's Town of James Island median was about $605,000 (all home types, June to August). Zillow's typical value for ZIP 29412 was about $598,000. All three are correct.

It depends on the question: the MLS for buying or selling in your area, Zillow for tracking value over time, Redfin for how fast homes are selling.

• Buying or selling a house: CTAR's single-family figures for your market area, looked at over several months (turn on the 3-month smoothing on the MLS areas tab in Market data).
• Tracking what your home is worth over time: Zillow's home value index for your town or ZIP. It moves smoothly and goes back to 2000.
• How fast homes are selling: days on market and months of supply from Redfin or CTAR.

Monthly. Zillow, Redfin and the MLS publish the previous month's data in the first half of each month, and the site is refreshed after that. Mortgage rates come from Freddie Mac's weekly survey.

Towns follow official town and city limits. Market areas are the local MLS's own zones (for example, "West Ashley" or "James Island"), which cross town lines. Neighborhoods are grouped by where they physically sit, so Riverland Terrace is listed under James Island even though it is inside City of Charleston limits.

Small places have few sales. When a median is based on a handful of homes, one expensive or cheap sale moves it a lot. We flag small samples with an asterisk (*). For small areas, look at the trend over several months rather than the latest dot.

Market notes say what the numbers did each month. The Beacon takes one question at a time and works through what they mean.

They are two halves of the same work.

• Market notes come out once a month, after the new figures post. They say what the numbers did: prices, sales, the Tide Gauge (our market conditions score) and mortgage rates, town by town.
• The Beacon takes one question at a time and works through what the numbers mean. It shows the math and the questions worth asking. It does not tell anyone what to do.

The free email is the monthly market note, sent mid-month. Beacon pieces are posted on the site and shared on Facebook and X, and the next market note links to any new ones.

The "Ask the Keeper" chat box answers questions about Charleston-area housing using only this site's data.

The Keeper is the "Ask the Keeper" chat box in the corner of every page. Type a question about Charleston-area housing, like "How is Summerville doing?" or "James Island vs. Mount Pleasant," and it answers from the same data shown on this site: 27 towns, the neighborhoods, ZIP codes, CTAR market areas, mortgage rates and the leading indicators.

• It only uses this site's data. Each answer names its source and month and links to the chart behind it. If the number isn't here, it says so.
• It refreshes with the site. When the monthly data updates, so does the Keeper.
• Questions are saved, anonymously. I keep the questions people ask (not names, emails or IP addresses) for up to 180 days, to see what readers want to know and to improve the site. Email addresses or phone numbers typed into a question are blanked out before saving.
• It can be wrong. It's an AI (Anthropic's Claude) reading a summary of the data. Check the linked chart before relying on a number, and email me if something looks off.
• It won't give advice or value your house. It explains what the numbers show, not whether to buy, sell or wait.
• It's free, up to 10 questions a day. Your questions are sent to Anthropic to generate the answer. Don't type personal details like your address or finances.

No. Cape Island Point Research is an independent publication. We aren't a brokerage, lender or agent. Use the numbers as a starting point, and talk to a professional about your specific situation.

Zillow doesn't publish a series for the Town of James Island, so we use its ZIP code 29412, which contains the whole town. Rockville uses its ZIP 29487 for the same reason.

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Email brandon@capeislandpoint.com. I read every message.

• Found a mistake? Tell me the page and the number that looks wrong, and it will be fixed in the next update.
• Have a suggestion? A town or neighborhood to add, a chart you'd like to see, or something that's confusing: I want to hear it.