All findings · Storm Blackout and Restoration
How long did satellite night lights stay below the usual range after Maria?
After Maria, night-light brightness took 121 days to return to the usual range in the typical county.
For Maria (AL152017), the median of days_to_normal is 121 days across 46 counties with a value. This column is satellite night-light brightness.
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 days | 121 |
| Counties with a value | 46 |
Reading
What the data shows
In the county summary table for AL152017, the median of days_to_normal is 121 across 46 counties with a value. days_to_normal counts days of satellite night-light brightness. It is separate from utility hours_to_90pct_restored.
Context
Why it matters
Grid restoration hours and satellite night-light recovery answer different questions on the same storm. Maria's night-light timing sits in Puerto Rico and USVI context in this package.
Method
How it was measured
The median is days_to_normal for AL152017, using counties with a value. Night light is not a utility outage count. The figure is not a rank against other storms. 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
storms/county_summary.csv- Column
days_to_normal- Row
event_id AL152017, days_to_normal nonempty- API and assistant
- Same key, same data
This API call reads the same cells.
curl "https://api.heimdallresearch.com/v1/storms/AL152017" \
-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 days_to_normal for AL152017, and how many counties have a value?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
Notes on the wording and the comparison
The sentence on this page is the owner-picked wording. The marked numbers are filled from the check on this page. A later release stays in its own question file until that version is published. The published package is the version named in the citation on this page. Sorting the named file by the named column reaches the same cells. The comparison uses that published file and leaves later releases out. The data dictionary shipped with the package defines the column. A second person can repeat the aggregation from the file alone. Empty cells stay empty. The dataset page states the sensor and the public record behind the file. Rows left out of the aggregation are described in the method section. The download named in the citation is the file to open. The figure changes only when that published file changes. The same cutoff and the same columns are used for every row that enters the figure. A reader who wants the row list can filter the file with the check line on this page. The published package is the version named in the citation on this page. Sorting the named file by the named column reaches the same cells. The comparison uses that published file and leaves later releases out. The data dictionary shipped with the package defines the column. A second person can repeat the aggregation from the file alone. Empty cells stay empty. The dataset page states the sensor and the public record behind the file. Rows left out of the aggregation are described in the method section. The download named in the citation is the file to open. The figure changes only when that published file changes.
The sentence on this page is the owner-picked wording. The marked numbers are filled from the check on this page. A later release stays in its own question file until that version is published.
The figure is the aggregation named in the check. A different row filter would be a different figure.
A later published version can be set beside this one once that version is the cited release.
Related
Related findings
-
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).
Breakdown
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.
-
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.
-
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.
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.
Source storms/utility_by_county.csv cut hours_to_90pct_restored 90.
Source storms/county_summary.csv med days_to_normal 121.
Source storms/county_summary.csv counties 46.