How can Oklahoma Mesonet soil moisture data explain foundations?

Reviewed by Preston, Oklahoma foundation repair consultant · Updated 2026-10-14

In short: The Oklahoma Mesonet is a free, statewide network of weather stations that reports rainfall, temperature and soil moisture for every county. Its soil moisture readings show whether the ground near a home is drier or wetter than usual, which helps explain why clay soils are shrinking or swelling. The sensors are shallow, so they show trends rather than conditions at foundation or pier depth.

What is the Oklahoma Mesonet?

The Mesonet was officially commissioned on January 1, 1994, and is a joint project of the University of Oklahoma and Oklahoma State University, operated by the Oklahoma Climatological Survey ¹. The current network has 120 stations ¹. Stations are located in all 77 Oklahoma counties at an average spacing of about 18 miles ². Rainfall is recorded every 5 minutes and soil moisture every 30 minutes ².

What soil moisture data does it report?

Sensor depths

Most Mesonet sites have four soil moisture sensors, at 2, 4, 10 and 24 inches (5, 10, 25 and 60 cm) below the surface ³. The 4-inch depth is the only one measured under both grass and bare soil ³.

Fractional water index

The fractional water index (FWI) is a normalized sensor reading that runs from 0 to 1 ³. On the Mesonet's maps, 0 means the soil is about as dry as the sensor can read and 1 means it is about as wet as the sensor can read ⁴. OSU Extension describes 0 as near the wilting point (plants can't pull water) and 1 as near field capacity (soil holding as much as it can drain to) ³.

A few practical notes from the sources:

• Soil moisture can't be measured when the ground is frozen, so winter maps can have gaps ⁴.
• The rate at which soil moisture falls reflects how hot and dry the air is; it drops faster in hot, dry spells ³.
• Comparing depths after a rain shows how deep the water soaked in ³.

Other useful readings

• Rainfall totals from the 5-minute gauges ².
• U.S. Drought Monitor categories (D0–D4), updated every Thursday and built partly from soil moisture data ⁵.

How does Mesonet data connect to foundations?

Expansive clay swells when it gets wet and shrinks when it dries, and uneven moisture under a slab causes differential movement, meaning one part of the house moves more than another ⁶. Oklahoma State University researchers have used Mesonet climate data to map long-term soil moisture conditions for foundation design across the state ⁶.

The limits matter. The deepest standard sensor is about 2 feet down ³, while studies of Houston-area clay sites judged seasonal moisture change to reach about 8–12 feet, deepening by about 2 feet during the 2011 drought ⁷. Mesonet readings therefore show whether the near-surface soil is unusually dry or wet, not the moisture at the depth where piers bear. More detail is on the active zone page.

Ways the data is commonly used

• Recording the nearest station's soil moisture and drought category on the date of an elevation survey or repair, so later surveys can be compared under similar conditions.
• Explaining why cracks open and close seasonally.
• Putting lift decisions in context: lifting while soil is at its driest can be followed by swelling when it rewets, as described under over-lift heave.

Related

• Drought and Wet Cycles
• Seasonal Movement Calendar
• OK Data - Moisture Index by City
• Monitoring Program