Forecast skill is a measure of accuracy and varies with months and regions. Forecasts are provided at several lead-times (e.g., a forecast made today for 1 week from now has a lead-time of 1 week). Skill declines with lead-time, for example, a 3-day weather forecast is more reliable than a 7-day forecast.
The figure below shows the expected skill of the forecasts shown on the SST Forecasts page, based on how well the forecasting model predicted SST in past years (1982-2010) for the same time periods and lead-times as shown. Here, forecast skill is being measured using correlation (r) , where:
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