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DMV Weather is 89.0% accurate

w/HIGH + LOW temp 4CASTS since 12/24/2017.


That's a total of

121 ACCURATE forecasts

out of 136 total forecasts made!

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Always Stay Weather Informed™.

Accuracy Matters!


89.57% ACCURATE (5/21/2017-12/28/2017)

HIGH TEMP ACCURACY = 91.83% (Began 5/21/2017)

  • *787 accurate forecasts in 857 total forecasts

LOW TEMP ACCURACY = 83.54% (Began 10/4/2017)

  • *269 accurate forecasts in 322 total forecasts

NOTE: Accurate = Forecast high and low temperatures ("Target Temps") are equal to, or within 4 degrees of, the actual temperature ("In Range") as measured by the National Weather Service at each of four specific locations across the DMV region: Annapolis, MD (U.S. Naval Academy), Baltimore, MD (BWI Airport), Dulles, VA (Dulles International Airport), and Washington, D.C. (Reagan National Airport).  When the forecast high/low temp equals the measured (actual) high temperature, it's called being "On Target."

The Stats

TOTAL 2017 4-Degree FOURcast™ Accuracy Stats (HIGH + LOW TEMPS)

LocationNWS StationIn Range3 or Less2 or Less1 or LessOn Target
Out of Range
001 OverallN/A89.57%80.15%63.44%42.49%15.95%10.43%
002 AnnapolisKNAK90.98%80.39%62.75%41.96%16.47%9.02%
003 BaltimoreKBWI87.34%77.92%61.69%43.18%14.94%12.66%
004 DullesKIAD87.66%78.25%61.04%41.88%15.26%12.34%
005 Washington, D.C.KDCA92.53%84.09%68.18%42.86%17.21%7.47%

TOTAL 2017 4-Degree FOURcast™ 4cast Results (HIGH and LOW TEMPS)

LocationNWS StationTotal 4castsIn RangeOn Target1 Away2 Away3 Away4 AwayOut of Range
001 OverallN/A11791056188313247197111123
002 AnnapolisKNAK245232426553452723
003 BaltimoreKBWI308269468757502939
004 DullesKIAD308270478259532938
005 Washington, D.C.KDCA308285537978492623


Central to the Weather Informant mission (DMV Weather is a division of Weather Informant) is the creation and implementation of a system of objective performance measurement in weather forecasting, which Weather Informant will call Capture and Compare™.

On May 21, 2017, DMV Weather (previously operating as CSC Weather since 2012) officially began forecasting for the DMV region based on its own new system of Capture and Compare™ - the above statistical charts represent the forecasts and their associated results since 5/21/2017, which formally represents the beginning of what will be an industry-changing approach where forecasts are submitted/posted ahead of time and are then graded - objectively - after the "event" happens.  In this case, the "events" contained in the above charts are for daily high temperature forecasts for four locations across the DMV region: Annapolis, MD (NWS reporting/observation station at the U.S. Naval Academy), Baltimore, MD (NWS station at BWI Airport), Dulles, VA (NWS station at Dulles International Airport) and Washington, D.C. (NWS station at Reagan National Airport).


The DMV Weather high temperature forecasting is done with a min-TARGET-max approach that involves submitting/posting a very specific high temperature forecast for each day (called the Target Temp) for the next day's high temp at each of the four locations listed above in the DMV and includes a +/- 4-degree variance for an overall accuracy rating (in a graphic called "The 4-Degree FOURcast™).

As an example, a high temp forecast of 80 degrees (target temp) has an accuracy range of 76 degrees to 84 degrees that comes with it (the +/- variance of four degrees), giving an overall accuracy range for the forecast.  But the analysis of the forecasting goes way beyond the accuracy rating based on target temps with a +/- variance of four degrees; the statistics also show how many times the forecast target temp exactly matched the actual temp, how many times it was only one degree away from actual...two degrees away...three degrees away...etc. in an effort to paint a complete picture of overall forecast performance.  This same approach will ultimately be expanded to other measurable weather variables such as low temps, wind speeds, rainfall and snowfall amounts, and so on.

With that in mind, the forecasts highlighted in green are accurate (they either specifically hit the target temp or they fell within the +/- 4-degree range), whereas those highlighted in red were inaccurate (they fell outside of the acceptable variance/accuracy range, meaning they were five degrees or more away from the Target Temp).  Those highlighted in orange were "on target," or "bulls-eye" forecasts in which the forecast target temp exactly matched the actual NWS recorded temp for a particular location.

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