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Severe weather plan for outdoor events: a go/no-go decision tree for company events

By the Vantly team · Updated October 16, 2026

The forecast notification arrives at 6 a.m., and the lunch is on the lawn. A severe weather plan means that moment is a check, not a debate. It is written before the event and names one decision owner, a separate weather monitor, fixed check times against official forecasts and alerts, the trigger for each action, a held indoor backup and a message ready for every outcome. On the day, you follow the plan. This guide is for anyone running an outdoor block inside a company event: a team activity, a lawn lunch, a rooftop reception in Manhattan or a tented dinner in the Hudson Valley. It works the same way anywhere in the US. It is general planning guidance, so follow official alerts and the venue's instructions whenever they say something different, and in an emergency, call 911 first.

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A covered park pavilion with warm lights glows beneath a dark, misty grey sky. Rows of picnic tables sit under its roof beside a wide open ground lined with leafy trees.
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The go/no-go decision tree

At every check time, the weather monitor reads the official forecast and alerts, compares them with the triggers you agreed in advance, and the decision owner picks one branch. The triggers below use the names of official National Weather Service (NWS) products and the NWS lightning criteria rather than numbers we picked. Where a branch depends on your venue, agree the trigger with the venue when you sign.

Go/no-go decision tree for an outdoor company event: trigger, action, who decides and who is told.
BranchTypical triggerWhat happensWho decidesWho is told
Go as plannedNo watch, warning or advisory covers the event window, and none of your agreed triggers is metRun the outdoor block as planned and keep the next check timeDecision ownerNobody new; the monitor keeps watching
Go with adjustmentsA Heat Advisory, a Severe Thunderstorm Watch, or rain in the forecast for part of the windowShorten or move the outdoor block, add shade and water, put the backup on standbyDecision ownerAttendees, venue, caterer
Move to the indoor backupThunder heard, lightning seen or threatening skies; a Severe Thunderstorm or Tornado Warning; an Extreme Heat WarningMove everyone to the backup space and run the block thereDecision owner; the monitor can stop activity on the spot for lightningAttendees, venue, caterer, AV
Delay and reassessLightning has stopped the activity, or a storm is expected to passHold indoors and recheck at a set time; resume outdoors no sooner than 30 minutes after the last thunderDecision ownerAttendees, venue
Postpone or cancel the outdoor blockAn Extreme Heat Watch or warnings expected across the whole window, or a backup that cannot do the same jobDrop or reschedule the outdoor block and keep the rest of the programDecision owner, with the sponsor if money is at stakeAttendees, venue, every vendor on that block
Tell people not to travelOfficials advise against travel in the areaStop arrivals, switch to a remote or rescheduled format, cancel transportDecision owner and sponsorEveryone, as early as possible

The printable version of this tree adds a fill-in header for the decision owner, backup owner, weather monitor, check times, backup space and its activation deadline, and the venue and transport contacts. Print it, fill it in when you sign the venue contract, and attach it to your run of show.

Name the decision owner and a separate weather monitor

Give the call to one person, with a named backup, and agree their spending authority in advance so they can switch to the indoor space without waiting for approval. Usually this is the event lead, not the most senior person in the room.

Then name a different person to watch the weather. The NWS guidance on lightning safety for organized outdoor activities says the lightning monitor "should not be the coach, umpire, or referee, because these people will be busy and can’t adequately monitor conditions." For a company event, that means someone other than the person running the session or the activity. The monitor watches the sky and the alerts; the decision owner makes the call.

When to check: a fixed check-time ladder

Write the check times into the run of show, so nobody has to remember to look. A simple ladder:

  1. When you book: ask the venue and each outdoor vendor for the latest time they need a decision to switch, and write it down. That deadline sets your last check.
  2. The week before: look at the outlooks and the extended forecast, and confirm the backup space is still held.
  3. The day before: check the forecast for the event window, decide whether the outdoor block runs as planned or with adjustments, and send any change to attendees with their day-before notes.
  4. The morning of: check again before attendees leave for the venue, so nobody is already on the road when you change the plan. If your group is already on site, check before the venue starts setting up outside.
  5. Before the outdoor block starts: a final check against your triggers, then the monitor keeps watching throughout.

The day-before check fits naturally into the company offsite day-before runbook, and the first-time EA offsite checklist has the rest of the timeline.

What to watch: official US sources

Use official sources and the same ones at every check, so the call is consistent:

  • Your local NWS forecast office for the forecast and for watches, warnings and advisories. Enter the venue's location on weather.gov to find it; for a New York–area event, that is the NWS New York office.
  • The NOAA Storm Prediction Center for thunderstorm outlooks in the days ahead.
  • NWS heat alerts and HeatRisk for heat (more below).
  • Local emergency alerts from the city or county where your event is, such as Notify NYC in New York City.

The difference between a watch and a warning drives most decisions. In NWS wording on severe thunderstorm watches and warnings, a watch means "Be Prepared! Severe thunderstorms are possible in and near the watch area," and a warning means "Take Action! Severe weather has been reported by spotters or indicated by radar." The tornado watch and warning follows the same logic: a warning means "A tornado has been sighted or indicated by weather radar."

"Severe" has a specific meaning. The Storm Prediction Center defines a severe thunderstorm as one "producing hail that is at least 1 inch in diameter or larger, and/or wind gusts of 58 mph or greater, and/or a tornado," and notes: "Although lightning can be deadly, the NWS doesn't use it to define a severe thunderstorm." That matters for your plan: a storm with no warning attached can still stop your outdoor block, because lightning alone is reason enough.

Lightning policy for outdoor events

A lightning policy answers five questions, the ones NWS asks of organized outdoor activities: when activities stop, where people go, when they resume, who monitors and decides, and what to do if someone is struck.

When to stop. NWS lists three criteria: if you see lightning, if you hear thunder, or if the skies look threatening. The current NWS rule is short: "When Thunder Roars, Go Indoors." If you hear thunder, NWS says on its lightning safety tips page, "you are likely within striking distance of the storm." Don't start an outdoor activity you can't stop quickly when a storm is building.

Where to go. NWS says "Substantial buildings with wiring and plumbing provide the greatest amount of protection," and, without one, "a hard-topped metal vehicle with the windows closed provides good protection." Tents, pavilions and porches are not shelter. The NWS Greenville-Spartanburg office puts it plainly: they "DO NOT offer any lightning protection whatsoever and may actually increase your danger of being struck." Allow time to move the whole group, and know the route before the event.

When to resume. NWS advises waiting "at least 30 minutes after the last thunder before resuming outdoor activities." The count starts from the last thunder you hear, so a new rumble means a new 30 minutes.

Who decides. The weather monitor can stop activity on the spot; the decision owner decides what happens next.

If someone is struck. NWS says: "Call 911 for medical help. Victims do not carry an electrical charge." That means people nearby can help right away.

For venue and vendor staff working outside, the OSHA and NOAA fact sheet on lightning safety when working outdoors asks employers for a written lightning safety protocol, and it reminds them to account for the time it takes to evacuate members of the public. Ask your venue whether it has one, and make sure your plan matches it.

Heat plan for outdoor company events

Plan the program around heat from the start rather than reacting to it on the day. A heat plan usually changes a few things at once: it moves outdoor blocks earlier or shortens them, adds shade and water, builds in rest, offers a lower-exertion option and an indoor alternative, and tells attendees what to wear.

Tie those changes to official alerts. NWS issues three heat products, described on its heat watch, warning and advisory page:

  • Heat Advisory: "Consider postponing or rescheduling outdoor activities, especially during the heat of the day."
  • Extreme Heat Watch: "Plan to suspend all major outdoor activities if a warning is issued."
  • Extreme Heat Warning: "Avoid outdoor activities, especially during the heat of the day."

These replaced the older "Excessive Heat" names on March 4, 2025, so older plans may still use them; NWS explains the change. There is no single national heat-index number that triggers an alert, because each local NWS office sets its own criteria. Your plan is clearer if it follows the alert rather than a number.

For an earlier look, NWS publishes HeatRisk, an experimental product that rates expected heat from green (little to no risk) to magenta (extreme). It is useful at the week-before check, alongside the official alerts.

If you want a sense of the numbers behind the alerts, NWS publishes heat index categories, shown here from the NWS Amarillo office. The heat index is measured in the shade, and the NWS heat index page notes that "exposure to full sunshine can increase heat index values by up to 15°F."

NWS heat index categories (heat index in °F, measured in the shade).
CategoryHeat indexWhat NWS says is possible
Caution80°F - 90°FFatigue possible with prolonged exposure and/or physical activity
Extreme Caution90°F - 103°FHeat stroke, heat cramps, or heat exhaustion possible with prolonged exposure and/or physical activity
Danger103°F - 124°FHeat cramps or heat exhaustion likely, and heat stroke possible with prolonged exposure and/or physical activity
Extreme Danger125°F or higherHeat stroke highly likely

OSHA and CDC guidance on heat is written for workers, so it applies directly to the venue staff, caterers and crew working your event, and it is a useful reference point for guests. OSHA encourages "water, rest, and shade as prevention as well as treatment for heat-related illness." Its guidance on heat hazards notes that "Direct sunlight can increase Heat Index by up to 13.5°F (7.5°C)" and prefers on-site WBGT measurements (wet-bulb globe temperature, which also accounts for sun and wind) over the heat index. For a quick reading on the day, the NIOSH/OSHA Heat App gives a heat index reading (not WBGT) on your phone. For staff doing moderate work in the heat for less than two hours, CDC/NIOSH recommends drinking "1 cup (8 oz.) of water every 15–20 minutes," and says "fluid intake should not exceed 6 cups per hour."

People react to heat differently, so make the lower-exertion option and the shaded or indoor alternative easy to choose without explanation.

Indoor backup: what to hold and confirm

The backup has to do the same job as the outdoor plan. If the outdoor block is a seated lunch for 40, the backup must seat 40 for lunch, not just keep them dry. Our guide to venue capacity for sleeping, meeting and dining explains how to check that a space really fits the group.

Confirm these in writing when you sign:

  • The space, held for your time slot, and what it can be set up for
  • The cost or fee to activate it, if any
  • The latest time the venue needs your decision
  • Who moves the furniture, the catering and the AV, and how long it takes
  • How transport changes if the location changes
  • An accessible route to the backup and an accessible space, as covered in our venue accessibility checklist

Rain, wind and tents

A tent is a rain plan, not a lightning plan. It keeps people dry and shaded, but it is not shelter in a thunderstorm, as the lightning section explains.

Wind limits depend on the structure, and no single government figure applies to every tent. Ask your tent or structure vendor for its written weather and evacuation policy, including its wind limits, and put it in your plan. For example, American Tent's setup guide for one of its tents says that if winds are predicted to "exceed 38 mph in 6 second gusts, the tent must be evacuated." Your vendor's own limit is the one that governs your event.

When authorities advise against travel

If official alerts advise against travel, tell attendees not to set out, as early as you can, and switch the affected part of the program to a remote or rescheduled format. Confirm cancellations with the transport company and the venue, and check what happens to anyone already en route. Our guides to group transport for company offsites and the attendee traveler guide cover the logistics on both sides.

The messages to send

Write these before the event, so the decision owner only has to fill in the times. Send them from one channel attendees already watch, and copy the venue and vendors on their own short version.

  • Go with adjustments: "Today's outdoor session is on, with a few changes: it now runs from [time] to [time], there's shade and water on site, and an indoor option if you'd prefer. Light clothing and sun protection recommended."
  • Move indoors: "We're moving [session] indoors to [space] because of the weather. Same time, same plan. Please head there now; the team will guide you."
  • Delay: "We're pausing outdoor activities because of lightning in the area. Please stay indoors at [space]. We'll update you at [time]."
  • Postpone the outdoor block: "Because of [heat / storms] forecast for this afternoon, we're replacing [activity] with [alternative] at [time and place]. The rest of the program is unchanged."
  • Do not travel: "Officials are advising against travel in [area] today, so please don't set out. We'll join remotely at [time] instead, and the link is below. We'll share new dates soon."

Contracts and money: ask before you sign

Weather decisions cost less when the contract already answers them. Before you sign, ask:

Anything with money at stake should be confirmed by Finance, Legal or your insurance broker.

Where a local event designer helps

Outdoor plans are easier to protect when the backup is part of the design from the start. With Vantly, a local event designer who knows the destination can hold a real indoor option, brief the venue and vendors on your decision time, and move the program if the call is made. Our intent is one vendor, one PO for the event, rather than a separate contract and deposit for every vendor. You can see sample events as examples a designer tailors to your team, or browse local event designers by destination. For a day built around an outdoor activity, our team building day page shows the format, and the corporate retreat guide covers longer programs. To build the outdoor blocks into your schedule, start from the offsite agenda template.

Want a plan with the backup already built in?

Tell us your dates, headcount and the outdoor moments you have in mind, and a local event designer will put together a tailor-made proposal with the backup included. Get a custom quote.

Frequently asked questions

Who should make the weather call for a company event?

One named decision owner, with a backup, agreed before the event and given spending authority for the indoor switch. A different person should watch the weather, as NWS recommends for organized outdoor activities, so the call never waits on someone busy running the program.

When should we decide to move an outdoor event indoors?

At fixed check times written into the run of show, using official forecasts and alerts. Your last check comes before the venue's own decision deadline. If an agreed trigger is met at a check, you move; you don't wait to see whether it clears. Thunder, lightning or threatening skies mean moving at once.

What is the 30/30 rule for storms?

The 30/30 rule is older guidance. Current NWS advice is simpler: when you hear thunder, go indoors right away, without counting seconds, and wait at least 30 minutes after the last thunder before going back outside. Counting from flash to thunder now only estimates how far away the lightning is.

What should a lightning policy for an outdoor event say?

It answers five questions: when activities stop, where people go, when they resume, who monitors and decides, and what to do if someone is hurt. NWS advises stopping when you see lightning, hear thunder or the skies look threatening, sheltering in a substantial building or hard-topped vehicle, and waiting at least 30 minutes after the last thunder.

Is a tent safe shelter during a thunderstorm?

No. NWS says tents, picnic pavilions and porches offer no lightning protection. A substantial building with wiring and plumbing is the safe option, or a hard-topped metal vehicle with the windows closed. A tent is a rain and shade plan, not a lightning plan.

What should a heat plan for an outdoor company event include?

Earlier or shorter outdoor blocks, shade, water, rest, a lower-exertion option and an indoor alternative, plus a note on what to wear. Tie the changes to official NWS heat alerts, a Heat Advisory, Extreme Heat Watch or Extreme Heat Warning, rather than a number you picked, since local offices set their own criteria.

What should the indoor backup space be able to do?

Seat the whole group for the same purpose, whether that's the meal, the session or the activity, not just keep them dry. Confirm in writing the space, the cost to activate it, the venue's decision deadline, who moves catering and AV, and how transport changes.

What if authorities advise against travel on the day?

Tell attendees not to travel, as early as you can, and switch to a remote or rescheduled format. Confirm cancellations with transport and the venue, and check what the contract says about weather and date changes. Finance or Legal should confirm anything with money at stake.

Sources

All sources checked October 16, 2026.