Climate Trends

OCS's Climate Trends graphics show the evolution of Oklahoma's climate history since the modern record began in 1895.

Each graphic shows the evolution of precipitation or temperature since 1895 for one of ten regions: any of Oklahoma's nine climate divisions, or the statewide-averaged value. The product is the result of a partnership with the USDA-ARS, Grazinglands Research Laboratory in El Reno. The mission of the GRL is to help the agricultural community select the most appropriate varieties of crops and the most appropriate land management practices. Obviously, when Mother Nature changes the rules and the timing of climate, this can impact decisions that are made over the course of years. These time-series are tuned to a five-year cycle, the time scale in which these decisions and developments occur. Please read the companion report about these climate variations.

The graphics are also available for a number of periods. Selecting "Annual" gives exactly that: a year-by-year average temperature or total precipitation. Individual months show the evolution of climate only for that month. Seasonal selections represent the aggregation of three-month rainfall or average temperature (Spring-MAM, Summer-JJA, Autumn-SON and Winter-DJF). Winter spans parts of two calendar years, but is named for the year during which it ends (e.g., Winter 1956 represents December 1955, plus January and February 1956).

In each graph, the observed value for each month, season or year is plotted as a dark diamond. The colored traces represent the five-year weighted average. Periods during which the five-year weighted average value was greater than the long-term average are shaded in green (precipitation) or red (temperature). Periods during which the five-year weighted average was less than the long-term average are shaded in brown (precipitation) or blue (temperature).

Example: Selecting "CD6 East Central", "Precipitation" and "July" will return the history of July rainfall in east-central Oklahoma since 1895. The diamonds represent the July rainfall in the region for each year. The green-brown trace represents the five-year weighted average July rainfall over time. The large green spike in the early 1960s is a dramatic increase in this weighted average. This increase was strongly influenced by very large rainfall values observed in July 1959, July 1960 and July 1961, as well as above-average observations in July 1958, July 1962 and July 1963.

Example: Selecting "CD8 South Central, "Temperature" and "Seasonal Winter" will return the average temperature for each complete DJF period from 1895 until present. The trace begins with the 1895-96 seasonal value, because the modern record does not include December 1894.

Example: Selecting "Statewide", "Precipitation" and "Annual" will return the annual precipitation for each year since 1895.

For more details about these or other OCS climate products, please contact OCS's Climate Information Group.