Definition
An unscheduled aviation weather observation issued between routine hourly METARs when a significant change in conditions occurs at the reporting station — for example, a sudden shift in wind, a drop in visibility or ceiling below specified thresholds, the onset or end of thunderstorms or freezing precipitation, or other operationally significant changes. A SPECI uses the same coded format as a METAR; the only difference is the report-type identifier 'SPECI' in place of 'METAR' at the start of the report.
Plain English
An off-schedule weather report from an airport, sent out between the regular hourly reports because something at the field changed enough to matter — like the wind shifting, visibility dropping, or a thunderstorm starting.
Context Anchor
Seen in aviation weather reports, flight planning, and preflight weather checks for airport conditions.
Derivation
From the Latin 'specialis,' meaning 'particular' or 'out of the ordinary.' A SPECI is exactly that — a particular, off-cycle weather report issued because something noteworthy happened, rather than the routine hourly METAR.
Why Pilots Care
Gives pilots immediate notice of weather changes that could affect takeoff, landing, or route decisions.
Intuition Check
SPECI does not mean the airport is automatically unsafe or closed. It means the weather changed enough that an updated report was issued before the next regular report.
Example Sentence 1
While taxiing for departure, the pilot heard ATIS update with a new SPECI reporting wind gusts to 35 knots and visibility down to one mile in a thunderstorm.
Example Sentence 2
Before takeoff the pilot reviewed the latest SPECI to confirm the updated wind and ceiling.