A weather forecast is a scientifically based assumption about the future state of the weather at a certain point or region for a certain period. Compiled (developed) by meteorological services based on meteorological methods .
Forecasts are divided according to the lead time of the period for which the forecast is given
- nowcasting (nowcasting) — from 0 to 2 hours;
- ultra-short-term (SKPP) – up to 12 hours;
- short-term (KPP) – from 12 to 72 hours;
- medium-term (MTP) — from 72 hours to 10 days;
- with an extended period – from 10 to 30 days;
- long-term (LTP) – from 30 days to two years; include monthly, three-month (or 90-day), seasonal outlooks, which are a description of the average meteorological parameters, expressed as a deviation (deviation, fluctuation, anomaly) from climatic values, respectively, for this month (not necessarily for the upcoming month), for this 90-day period (not necessarily for the next 90-day period), for this season;
- climate forecast – over two years;
- climate forecast for a year to a decade (description of expected climate parameters associated with changes in interannual and decadal climatic anomalies, as well as anomalies of several decades);
- climate forecast (description of the expected future climate, taking into account the influence of natural and anthropogenic factors).
The accuracy of forecasts is the lower, the higher the lead time. The accuracy of the SPP is approximately 95–96% ; the SPP is 85–95%; the SPP is 65–80%;