The cold weather sometimes gives the impression that thunderstorm season is over. However, a winter shower, a coastal disturbance, or a snowfall can still be accompanied by electrical activity. For an operator, this possibility is more important than the typical image of a summer thunderstorm.
Internationally, the cold season does not correspond to the same months, nor to the same weather conditions. Therefore, a calendar designed for a headquarters located in the Northern Hemisphere cannot be replicated without adaptation across all sites within a group.
A robust organization therefore reasons from the local climate and observed conditions, rather than from an administrative closure of the "lightning season".
This article explains why ground temperature alone is insufficient to rule out a thunderstorm, what historical studies actually allow us to conclude, and how to prepare for outdoor activities outside of peak season. It also distinguishes between building protection, early warning systems, and monitoring of installations. The aim is not to announce an unproven increase in winter lightning, but to eliminate a blind spot in prevention efforts.
Can there be lightning when it's cold?
Yes: a cold atmosphere near the ground can coexist with updrafts and electrically active clouds. However, cold alone is not enough to produce lightning; a favorable atmospheric environment is also necessary. Therefore, the risk must be assessed based on the meteorological situation, and not solely on the perceived temperature.
The thermometer does not describe the entire atmosphere
Convection is a vertical movement of air that can promote the development of clouds and precipitation. High-level convection is convective activity that develops above a layer close to the ground; it helps explain why a cold surface does not preclude all thunderstorm activity at higher altitudes.
Indeed, a front or the terrain can contribute to the lifting of air. The environment at altitude, humidity, and vertical movements are therefore just as important as the perceived cold at the construction site.
The key takeaways are:
- a low ground temperature does not describe the vertical profile of the atmosphere;
- Winter precipitation does not automatically mean a lack of electricity;
- Low apparent activity does not allow us to rule out all impacts;
- A local event must be interpreted in light of the available meteorological information.
Therefore, "it's too cold for lightning" is not a safety rule. However, recognizing this limit does not mean that every snowfall is a thunderstorm.
Snow, freezing rain, and lightning: read the sources without generalizing
Storm snow is snowfall accompanied by electrical activity and thunder. It represents a special situation; not all winter storms involve lightning, and not all lightning strikes from a cold front occur within its snowy area.
A case study is not global climatology
The National Weather Service, the U.S. meteorological service, has published a landmark study by Steven M. Hunter, S. Jeffrey Underwood, Ronald L. Holle, and Thomas L. Mote on winter lightning in the southeastern United States. It examines seven events between 1994 and 1997, and the authors state that seven cases are insufficient to claim climatological representativeness (NWS, Winter Lightning Study).
Thus, this source verifies the existence of electrically active winter configurations, but does not provide a current probability for a European or African site. Its results are, moreover, presented by the authors as preliminary.
To read this type of publication correctly:
- Identify the region and dates of the cases examined.
- Distinguish between preliminary results and robust conclusions.
- Check if the lightning and precipitation are affecting the same area.
- Do not transform an observed association into a universal rule.
- Research local data before making a design decision.
Furthermore, the source describes varied atmospheric mechanisms depending on the episode. This serves as a reminder that the same label, "winter storm," can encompass very different patterns of rain, snow, and electrical activity.
Why low frequency can create a blind spot
Frequency and severity are not the same thing. Even if thunderstorms are less frequent over a given period at a location, the consequences of an event can still be significant for people and equipment.
A preparation tailored to the actual activity
For example, a port facility may maintain outdoor operations year-round. An industrial campus may also schedule work during the colder months to take advantage of reduced production; these illustrative examples demonstrate why task scheduling must be adapted to local conditions.
The preparation must simultaneously consider:
- people exposed in open spaces;
- the means of reaching a suitable shelter;
- difficulties in moving around due to ice or bad weather;
- the availability of decision-makers;
- the equipment necessary for communication and operation.
However, the goal is not to simply add up hazards in the abstract. It is to verify that the lightning protection plan remains feasible when other winter-related constraints slow down travel or disrupt communication.
Furthermore, a subcontractor present for only a few days must be familiar with the same rules as the permanent staff. A procedure that is forgotten because it is rarely used is less effective than a clear instruction repeated before the activity in question.
Alerting during the off-season, without confusing observation with a guarantee
An alert is information intended to trigger an action according to a defined procedure. A detection is the identification of an observed phenomenon; therefore, the information received must be interpreted according to the function and limitations of the service used.
Prepare the decision chain
Sky Sentinel provides continuous monitoring around a site, updating every 60 seconds, and sends storm alerts to recipients defined by the site. This decision support service, compliant with IEC 62793, helps in deciding whether to interrupt outdoor activity; it does not trigger any automatic actions and provides no physical protection.
However, no warning service can replace the choice of shelters, site responsibilities, or the effective means of ensuring people's safety. Sky Sentinel is not a protection device covered by NF C 17-102 and IEC 62305. It is a lightning monitoring and warning service compliant with IEC 62793.
Before any external intervention, organize the following steps:
- Consult the weather information relevant to the area.
- Check the recipients and methods of receiving alerts.
- Name the person authorized to stop the activity.
- Present the shelters and accessible routes under the current conditions.
- Define the conditions for resuming operations within the site's procedure.
The NWS also reminds us that lightning can cause power surges that can damage equipment, even at a distance from the strike, and advises against unplugging appliances during a thunderstorm (NWS, Indoor Safety). Therefore, if unplugging sensitive equipment is planned, it should be done before the storm arrives; during the storm, avoid handling appliances connected to the mains power supply.
Furthermore, Strike Radar allows users to retrospectively verify whether lightning strikes were recorded around a site on a given date, and to obtain keraunic reports and lightning strike certificates. It utilizes detection data that LPS France does not operate itself; therefore, it is not a tool for real-time monitoring.
These documents provide contextual information following the event. However, they do not, on their own, prove the integrity of all the equipment.
Maintaining consistent protection and monitoring throughout the year
The physical protection of the building and the safety of outdoor activities are two complementary issues. A lightning rod should therefore never be presented as a personal shelter for a team working nearby.
An international approach, then a local one
The IEC 62305 series, published by the International Electrotechnical Commission, provides an international framework for lightning protection. Part 4, IEC 62305-4:2024, deals specifically with protection measures for electrical and electronic systems; its third edition dates from 2024 (IEC, official presentation).
However, the choice of solutions depends on the installation and the applicable regulations. lightning rods Paraton@ir belong to the family of early streamer emission (ESE) lightning rods; their sizing is governed by NF C 17-102:2011 and a site study, not by meteorological articles.
Take advantage of the cold season to check the installation
Indeed, lightning protection works all year round. The cold season is therefore a good time to have the installation checked before the storm season, in particular:
- the impact counter reading;
- the continuity of downhill drivers;
- the fixings, after the storms;
- the condition of the lightning arresters;
- grounding connections.
Similarly, after a storm, even outside the storm season, the installation should be checked: lightning rod test, strike counter reading, surge protector check, and, if necessary, verification with Strike Radar of strikes that occurred around the site. The inspection frequencies are governed by IEC 62305-3 and NF C 17-102.
Next, LPS Manager, the application for monitoring connected products LPS France, centralizes the status of Paraton@irimpact counters Compt@ir and Alert@ir XT. It groups together reported faults, recorded impacts and warranty tracking, with a time-stamped history per installation.
The system Contact@ir allows for testing Paraton@ir without going onto the roof and for monitoring them remotely, either via radio to a Rout@ir or via cellular network with the Contact@ir MD. However, it does not constitute a storm snow forecast or a guarantee of external safety.
In summary, cold ground conditions do not eliminate all conditions conducive to lightning strikes. Historical studies show varied situations, without allowing generalization to all climates. Therefore, teams must maintain an alert system and guidelines applicable outside of peak season, while ensuring physical protection is appropriate for the site and regularly inspected. Contact LPS France to define your project, and monitor your connected lightning rods year-round with LPS Manager.
