The OSHA Compliance Framework for Lightning
There is no standalone numbered OSHA lightning standard. Section 5(a)(1) of the OSH Act requires each employer to furnish employment and a place of employment "free from recognized hazards that are causing or are likely to cause death or serious physical harm" to employees.
Employer duties depend on applicable law and worksite facts. OSHA and NOAA provide practical recommendations for recognizing and reducing outdoor lightning hazards.
The primary practical compliance reference is the OSHA and NOAA fact sheet OSHA 3863: Lightning Safety When Working Outdoors. It defines recommended planning, shelter, monitoring, and training procedures for outdoor worksites.
What the InfoSheet Recommends
- Written Emergency Action Plan (EAP) for lightning, with named decision-makers and clear shelter locations for each crew and worksite.
- Check NOAA weather reports before outdoor work and monitor weather conditions while workers are exposed.
- Postpone outdoor work when thunderstorms are likely. When workers hear thunder, move them to safe shelter immediately.
- Wait at least 30 minutes after hearing the last thunder before leaving shelter.
- Designated safe shelter — substantial building or hard-topped vehicle. Open shelters, tents, and dugouts do NOT qualify.
- Worker training on lightning recognition, the audible-thunder shelter trigger, and return-to-work procedures.
Thunder-Based Shelter Rule for Workplaces
OSHA and NOAA guidance treats audible thunder as the shelter trigger:
- Suspend outdoor work and move to designated shelter when thunder is heard.
- Resume only 30 minutes after the last audible thunder.
A lightning-detection service may supplement a worksite plan, but it does not replace audible thunder, official forecasts and warnings, or the employer's responsibility to provide suitable shelter and training.
Shelter Definitions for Compliance
| Shelter | OSHA / NOAA fact-sheet guidance |
|---|---|
| Substantial building (with plumbing + wiring) | ✅ Acceptable |
| Hard-topped vehicle (windows closed) | ✅ Acceptable |
| Open shelter / picnic pavilion | ❌ Not acceptable |
| Tent / canopy | ❌ Not acceptable |
| Athletic dugout | ❌ Not acceptable |
| Tractor / open-cab equipment | ❌ Not acceptable |
Detection + Alerting Tools That Support Compliance
- NOAA Weather Radio with SAME alerts — county-level severe-thunderstorm and tornado warnings issued by local NWS office.
- Commercial lightning detection services — may supplement weather monitoring, subject to provider limitations and the employer's site-specific plan.
- Free NOAA GOES East/West GLM lightning maps — useful for supplemental situational awareness, but not sufficient by themselves for compliance, all-clear decisions, or official warnings. Browse our all 50 state lightning maps or review the data limitations.
- NWS forecast and SPC outlooks — for daily planning; should be checked at the start of each shift.
Worksite Review Checklist
Lightning-related enforcement depends on the facts, applicable duties, and current agency guidance. Common gaps a workplace review should check:
- No written lightning EAP.
- Failure to suspend work despite audible thunder / visible lightning.
- Inadequate or non-existent shelter.
- No daily weather monitoring.
- No worker training on lightning hazards.
Verify current requirements with OSHA and qualified safety counsel for the specific worksite.