All findings · Storm Blackout and Restoration
How long did Irma counties take to reach 90 percent restored?
After Irma, the typical county reached 90% of customers restored in 53 hours.
For Irma, the median county hours to 90 percent restored is 52.9 hours (280 counties with a numeric value).
These numbers are Storm Blackout and Restoration version 1.2, the published package (672 storms in version 1.2).
Table
From the table
| Figure | Value |
|---|---|
| Median hours | 52.9 |
| Counties with a value | 280 |
Reading
What the data shows
For AL112017, the median of numeric hours_to_90pct_restored is 52.9 hours across 280 counties. Blank and non-numeric cells are left out. A row with reporting_drop true stays in the median when the hour cell is numeric.
Context
Why it matters
If you need both clocks on Irma, read this next to the Maria night-light finding. Utility restoration timing and night-light timing are not the same measure.
Method
How it was measured
The median uses hours_to_90pct_restored for AL112017 on rows with a numeric value. A row with reporting_drop true stays in when its hour cell is numeric. Method on the dataset page.
Limits
What this cannot tell you
Night light is not a utility outage count. County peaks can double-count customers across overlapping service territories when summed. Disclaimer word for word: Not for real-time emergency response or for any decision about one address or property.
Check
Check it yourself
- File
release/irma_hours.csv- Column
hours_to_90pct_restored- Row
event_id AL112017, hours_to_90pct_restored nonempty- API and assistant
- Same key, same data
This API call reads the same cells.
curl "https://api.heimdallresearch.com/v1/storms/AL112017" \
-H "Authorization: Bearer $HEIMDALL_API_KEY"This assistant prompt asks for the same cells.
MCP https://api.heimdallresearch.com/mcp question: What is the median hours_to_90pct_restored for AL112017?Citation
Dataset citation
Heimdall Research (2026). Storm Blackout and Restoration (Version 1.2) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.23010005 Concept DOI https://doi.org/10.5281/zenodo.23010004.
- Version
- 1.2
- DOI
- 10.5281/zenodo.23010005
Related
Related findings
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44 of 672 storm events are tropical cyclones or typhoons.
These 672 storm events include 36 with kind tropical and 8 with kind typhoon (44 together). Kind tropical includes hurricanes. Other counts: severe storms 347, floods 186, tornadoes 24, ice storms 21, winter storms 21, snowstorms 20, straight-line wind 6, coastal storms 3.
Breakdown
Counting kind on storms.csv yields the mix above. The three largest summed county peaks are Irma, Helene, and DR-4586. Kind tropical includes hurricanes.
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Irma has the largest sum of county outage peaks among these 672 storm events: 8.9 million.
Among these 672 storm events, Irma (AL112017) has the largest sum of county peak customers out: 8,867,374 across 329 counties with a numeric peak. Each county contributes its own peak. Those peaks are not one simultaneous count of customers out.
Breakdown
Summing numeric peak_customers_out for event_id AL112017 gives 8,867,374 across 329 counties. That sum is the largest among the 672 storm events. Each county contributes its own peak. Those peaks are not one simultaneous count of customers out. The next sums are Helene 5,911,300, DR-4586 5,214,663, Ian 3,981,026, and Milton 3,736,269.
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Milton's sum of county outage peaks ranks fifth: 3.7 million.
Milton (AL142024) sums to 3,736,269 peak customers across 51 counties (5th largest sum). Each county contributes its own peak.
Breakdown
For AL142024, the sum of numeric peak_customers_out is 3,736,269 across 51 counties. That ranks 5th, behind Irma, Helene, DR-4586, and Ian. Each county contributes its own peak. Those peaks are not one simultaneous count of customers out.
Estimates from public records and satellite night light. Not for real-time emergency response or for any decision about one address or property.
Provided as is, without warranty of any kind.