About the observatory
Heatwave Tracker combines two methods with different responsibilities. Depth-First Search (DFS) identifies each connected heatwave as a space-time event. The Heatwave Physical Risk Index (HPRI) then places that event in a stated reference distribution so its hazard can be compared and ranked.
Two linked methods
DFS preserves the physical structure of a heatwave event. HPRI adds a comparison layer without replacing or redefining the DFS metrics.
Event detection
What belongs to the same heatwave event?
DFS follows neighbouring high-temperature grid cells through space and time. Connected active cells become a three-dimensional event object with a beginning, an end, a daily footprint, and a complete event boundary.
Hazard interpretation
How unusual is the event in a stated reference?
HPRI converts event-scale HWMS into a 0-100 percentile rank within a declared domain and baseline. The score shows relative physical hazard, while HWD, HWMA, and HWMM remain visible as diagnostics that explain the event's structure.
What the system can explain
Which hot grid cells form one coherent event rather than unrelated local exceedances.
Whether the event is persistent, spatially broad, locally intense, or a compound of several traits.
How duration, mean affected area, and mean magnitude combine in the event-scale HWMS.
Where an event sits within a specified historical, regional, or asset-local reference catalog.
How to read the evidence
Identify active high-temperature cells from the daily climate field.
Use DFS adjacency to form complete space-time event objects.
Calculate duration, footprint, mean magnitude, and cumulative event magnitude.
Normalize HWMS against an explicit HPRI reference domain and baseline.
Combine hazard with external exposure and vulnerability evidence when assessing financial risk.
Interpretation boundary
An HPRI of 96 means the event exceeds about 96% of comparable events. It does not mean 96% financial loss, crop loss, outage probability, or mortality.
Cross-region asset comparisons should use regional or asset-local reference catalogs rather than raw full-event HWMS alone.
Heatwave Tracker is a research event archive and risk-screening system. Official agencies remain the source for immediate high-temperature warnings.