An “Actual” is the daily aggregated observation record for a specific weather station and date. This record contains validated high/low temperatures (both MOS and 24-hour periods), total precipitation, wind speeds, and opacity values derived from a series of hourly observations.
An “Actual” represents the final, summarized “truth” for a 24-hour period, whereas an “HourlyActual” is the snapshot of conditions (temperature, dew point, wind) at a specific hour. Professionals search for “Actual vs. HourlyActual reconciliation” when a daily high temperature recorded in the “Actual” does not match the highest value seen in any individual “HourlyActual,” often due to the high occurring between the standard hourly reporting times.
Raw data from a weather station can sometimes be erroneous due to sensor spikes or bird interference. The “Actual” record used in the industry has typically undergone a validation process (automated or manual) to ensure the data is meteorologically consistent. For instance, an “Actual” record will be flagged if the high temperature is lower than the low temperature, or if the dew point exceeds the ambient temperature.
The “Actual” record often distinguishes between a “Calendar Day” (Midnight to Midnight) high and a “Synoptic” or “MOS” high (which might be 12Z to 12Z). This distinction is critical for energy traders and utility companies who search for “Actuals” to calculate Heating Degree Days (HDD) or Cooling Degree Days (CDD), where the specific 24-hour window used can change the financial outcome of a trade.