Oklahoma Heat Extremes

Heat Extremes

Data Limitations

Oklahoma generally has good quality long-term data records for temperature values, however, the consistency of cumulative years on record vary by station. The majority of stations consist of a large record dating back up to the 19th century, however, some station locations include gaps in records that could be subject to technical issues or changes in monitoring location.

Definition and Description

Heat Extremes
Definition

A heat wave is an occurrence of unusual hot weather (maximum, minimum, and daily average) over a region persisting at least two consecutive days during the hot period of the year based on local climatological conditions, with thermal conditions recorded above given thresholds (WMO 2016).

Note: There is no universally recognized metric for what constitutes a heat extreme. The World Meteorological Organization recommends characterizing a heat wave by its magnitude, duration, severity, and extent. Magnitude is defined as a thermal measurement such as maximum temperature, or combination of several measurements, exceeding certain threshold(s). These values must be determined by the local climatology. Other studies have used thresholds based on human physiological response to heat, such as consecutive days of maximum or minimum temperatures above a threshold.

Description

Heat extremes in the central United States occur when a dominant large-scale high-pressure system prevents the movement of other air masses into a region. The high-pressure contributes to intense heating from solar radiation, due to a lack of cloud cover, and light winds preventing the dispersion of heat, especially from urban areas. This results in both higher than average maximum and minimum temperatures.

Historical Data

Historical Climate Trends Tool

(1895-present) Southern Climate Impacts Planning Program

This interactive graphing tool shows annual, seasonal, and monthly temperature trends by state and climate division. It can be used to gain a general understanding of temperature trends and show previous periods of higher temperatures, as well as years of extreme temperature. It could also be used to help estimate the probability of future extreme temperature events.

1. On left side of screen (from top to bottom) select OklahomaClimate Division of InterestSeason of InterestTemperature. 2. For more information on how to interpret the chart, click on Chart Info.

Climate Extremes Tool -Temperature

(Period of record varies by station; up to ~120 years) Southern Regional Climate Center

This interactive tool shows temperature extremes at point locations. It can be used to show the severity of past events that have occurred in a region of interest. Highlighted below are two ways the tool can be used to analyze heat extremes:

(a) High temperature records by month: 1. On left side of screen (from top to bottom) select Records For A MonthHigh Max TemperatureMonth of InterestGo. 2. Mouse over icons for record details including station name, date of occurrence, and station period of record.

(b) All-time records: 1. Select All-Time RecordsHigh Max TemperatureGo. 2. Mouse over icons for record details including station name, date of occurrence, and station period of record. Note: For more information, select the Help or About tabs.

Temperature Trends Dashboard

(1970-2023) Southern Climate Impacts Planning Program

This tool shows temperature trends at individual stations across Oklahoma, including trends in extremely hot days, warm nights, seasonal extreme and average high/low temperatures, and cooling degree days, since 1970.

1. At the top of the tool, click the Extreme Heat, Warm Nights, Heating and Cooling Degree Days, Seasonal Averages, or Seasonal Extremes tab. 2. The default station is in Abilene, TX. To choose a station nearest to you, use the map on the right. Zoom in and click any of the blue dots to change stations. You can also select a station under the Station drop-down menu on the left of the page. 3. Use the graph to determine the trend (if any) for your selection. Solid lines represent significant trends. 4. Mouse over individual data points to view more information. 5. For seasonal selections, make sure you select a season in the Season drop-down menu on the left of the screen.

Heat Index Days and Hours

(1973-2023) Midwest Regional Climate Center

This set of maps depict the average number of days, day with 3 or more hours, and average number of hours per year with heat index values at or above a variety of thresholds (e.g., 95°F, 110°F, 105°F).

1. Near the top of the page, click on the map link of interest out of the three options: Average Number of Days, Days with 3 or More Hours, or Average Number of Hours. 2. Right above the map, mouse over the heat index value of interest to view the corresponding data on the map. 3. To interpret the colors, see the legend on the top right side of the map. 4. To view more detailed information, such as station data, click the Interactive GIS Maps button on the top right of the page.

Average Number of Days with Highs Above 90°F or 100°F; Cooling Degree Days

(1991-2020) Oklahoma Climatological Survey

These static maps show the average number of days per year when the high temperature is above 90°F or 100°F. There is also a map of the average annual cooling degree days between 1991-2020.

1. Scroll to the second row of maps on the page. 2. Click on Average number of days with highs above 90˚F (or 100°F), or Normal Annual Cooling Degree Days (CDD).

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