BELLE — A review of three decades of federal climate data shows average temperatures have risen across a five-county region of central Missouri, while precipitation has continued to fluctuate considerably from year to year.

The analysis includes Crawford, Gasconade, Maries, Osage and Phelps counties and covers 30 complete weather periods beginning in July 1996 and ending in June 2026. Rather than using calendar years, each period runs from July through the following June, so the latest data could be used.

For the analysis, annual countywide figures were averaged together to provide a single measure representing conditions across the area.

Data from the National Oceanic and Atmospheric Administration show the region was noticeably warmer during the most recent decade than during the first decade reviewed.

During the first 10 years, the five-county region had an average temperature of approximately 55.64 degrees.

During the most recent 10 years, that average increased to approximately 56.97 degrees, a difference of 1.33 degrees.

A separate analysis of the annual temperatures across the entire 30-year period also showed a warming trend. The region’s average temperature increased at an estimated rate of approximately 0.71 degrees per decade.

Across all 30 years, the overall average temperature was approximately 56.07 degrees.

The warmest July-to-June period occurred in 2011-12, when the five-county regional average reached approximately 59.01 degrees.

The second-warmest period was 2025-26, with an average temperature of approximately 58.71 degrees.

The 2023-24 period ranked third at approximately 58.61 degrees, followed by 2016-17 at approximately 58.36 degrees and 2015-16 at approximately 57.75 degrees.

Four of the five warmest July-to-June periods in the 30-year analysis occurred during the most recent decade.

At the other end of the scale, the coolest period was 1996-97, the first year included in the analysis. The average that year was approximately 53.11 degrees.

That measures approximately 5.9 degrees between the average temperature of the coolest period, 1996-97, and the warmest period, 2011-12.

The difference shows how much temperatures can vary from one year to another. It also illustrates why long-term climate trends are generally measured across decades rather than by comparing one unusually warm year with one unusually cool year.

The averages also reveal that the two warmest periods in the entire 30-year study were separated by 14 years.

The five-county region averaged approximately 43.22 inches of precipitation per July-to-June period across the three decades.

During the first 10 years of the study, the region averaged approximately 41.46 inches annually.

During the most recent 10 years, that increased to approximately 43.78 inches, a difference of approximately 2.31 inches.

As with temperature, a separate analysis of annual precipitation across the entire 30-year period showed a long-term trend. Based on that analysis, regional precipitation increased at an estimated rate of approximately 0.64 inches per decade.

Unlike temperature, however, precipitation totals changed sharply from one year to the next.

The wettest period was 2010-11, when the five counties averaged approximately 51.95 inches of precipitation.

The previous period, 2009-10, was nearly as wet, with a regional average of approximately 51.48 inches.

More recently, 2024-25 averaged approximately 50.25 inches of precipitation across the five counties, making it the third-wettest period in the analysis.

The 2016-17 period followed at approximately 50.05 inches.

The driest regional period was 1999-2000, when the five counties averaged approximately 32.12 inches of precipitation.

The 2013-14 period was the second driest at approximately 33.4 inches.

More recently, 2022-23 averaged approximately 34.98 inches, making it the third-driest period in the 30-year analysis.

The warmest period also stands out for another reason.

During 2011-12, when the average temperature reached a 30-year high of approximately 59.01 degrees, the five counties averaged only approximately 35.49 inches of precipitation. That made 2011-12 the fourth-driest July-to-June period reviewed.

The contrast demonstrates how dramatically conditions can change from year to year and why precipitation trends are more difficult to characterize than the temperature trend.

For example, the region went from approximately 51.95 inches of precipitation during 2010-11 to approximately 35.49 inches during 2011-12, a decline of more than 16 inches in a single year.

Similar swings have continued during more recent years.

The region averaged approximately 34.98 inches during 2022-23, followed by 43.64 inches in 2023-24 and approximately 50.25 inches in 2024-25.

Precipitation then fell to approximately 38.1 inches during the most recent 2025-26 period.

Those variations demonstrate that a long-term increase in average precipitation does not mean the region has steadily become wetter. Exceptionally wet periods have continued to occur alongside unusually dry ones.

The temperature data presents a more consistent long-term pattern.

The average temperature during the most recent decade was approximately 1.33 degrees higher than during the first decade studied. Four of the five warmest July-to-June periods in the analysis have occurred since July 2015.

The figures used in the analysis are based on countywide climate estimates produced by NOAA’s National Centers for Environmental Information.

They should not be interpreted as measurements from a single thermometer or rain gauge.

NOAA develops its county estimates using quality-controlled weather observations incorporated into a gridded climate system. That allows temperature and precipitation conditions to be estimated across entire counties, including areas where no individual weather station is located.

Weather observations in and around the five-county region have been collected at locations including Cuba, Hermann, Steelville, Vienna, Vichy and Rolla.

Individual weather stations can have different periods of operation, gaps in observations or changes in location. NOAA therefore does not rely on one fixed station to represent conditions throughout an entire county.

Countywide figures also may differ from the temperature or rainfall measured at an individual home, farm or business. Thunderstorms and heavy rainfall in particular can produce significant differences over relatively short distances.

For this analysis, NOAA’s countywide figures for Crawford, Gasconade, Maries, Osage and Phelps counties were averaged together for each July-to-June period to create one regional figure. That provides a consistent measure for examining how conditions across the five-county area have changed during the past three decades.

The clearest finding is in temperature.

The average temperature during the most recent decade was approximately 1.33 degrees higher than during the first decade studied. Four of the five warmest July-to-June periods in the analysis have occurred since July 2015.

Taken together, the figures show a clear warming pattern across the five-county region over the 30 years reviewed.

Precipitation also increased when the first and most recent decades were compared, but that increase occurred amid considerably greater year-to-year variation, with some of the wettest and driest periods in the study occurring relatively close together.