Frequently, you’ll hear questions like: Is this a record high? Is this a record snow? This is really asking “how does today’s particular event compare to previous events”? When you hear the answer, it should also include the time period that was used for comparison. That is because the longer the period of comparison, better you can judge how much significance to give a record-breaking event. For example, a new rainfall record for a station that started in 2000 won’t be as impressive as one for a station that has data back to 1900. Be particularly cautious of records that don’t include significant climate periods. Again, as an example, record highs in Kansas that don’t include the significant heat wave of 1930's only tell part of the story.
Mary Knapp, Weather Data Library