How to decide on a rain or wind plan B for an outdoor event
A rain or wind plan B without guesswork: when to check the forecast, how to read it and how to tell the client.
Deciding plan B for an outdoor event is not one decision but three moments. Three weeks out you look at that week’s history in that place and book plan B with a release date; 72 hours out you compare several models and decide with the client using an agreed rule (rain, gusts, heat); and on event day you watch the radar and the official forecast with a clear cut-off time. What usually fails is not the forecast. It is never agreeing who decides, on what basis and at what cost.
We have seen black skies at 5 pm turn into perfect weddings at 7, and sunny cocktails ruined by a gust nobody checked. This is our system.
1. Plan B is decided before you look at the sky
Before opening any forecast, plan B must exist on paper:
- What it is: indoor room, marquee, awnings, a schedule change or a reordered programme.
- What it costs, and whether you pay only if it is activated.
- The deadline to activate it: a marquee needs days to install, the indoor room may have another booking.
- Who decides: you recommend, the client approves. Name and phone number.
- The rule: for example, “if 72 hours out most models show rain during the ceremony slot, we switch to plan B”.
Put plan B as an optional line in the Planner budget from the first version, so the client sees it and the invoice is no surprise.
2. When to check the forecast (and what to expect)
| When | What to check | What you decide |
|---|---|---|
| 3 weeks or more | Climate history for that week and time slot | Whether to hold a marquee or room, and the release date |
| 10 to 7 days | Global model trend | Warn the client it needs watching, if so |
| 72 to 48 hours | Model consensus, high resolution, official forecast | Main call: plan A or plan B |
| 24 hours | Hourly official forecast, wind and warnings | Adjustments: ballast, timings, umbrellas, shade |
| Event day | Radar, official forecast, the sky | Cut-off for whatever can still be reversed |
More than a week out, no forecast can tell you whether it will rain at 7 pm on a given Saturday. What you have is climate: how that week usually behaves in that place. In Meteo Murphy, when there is no reliable forecast yet, 20 years of history (Copernicus ERA5 reanalysis) for your slot and week leads. As the date gets closer, the high-resolution models kick in.
Note: inside 72 hours, your local official forecast and the radar have the final word. A decision tool is not a guarantee, and it is worth telling the client exactly that.
3. Models and consensus
The major models (ECMWF, NOAA GFS, DWD ICON, Météo-France, Met Office, Environment Canada and JMA) calculate the same thing with different methods.
How we read them:
- If nearly all agree, the forecast is solid, even when it is bad.
- If they split, there is uncertainty: wait if you can, and if you cannot, lean to the cautious side.
- The median beats the extreme: do not plan on the most pessimistic or the most optimistic model.
- Read the time slot, not the day: “rain on Saturday” is not “rain on Saturday from 4 to 6 am”.
- Read millimetres, not only percentages. A 70 % chance of a few drops is less of a problem than 40 % of a heavy shower.
Meteo Murphy queries those models live for your venue (not your city: a valley and a beach 20 km apart can have very different weather) and shows the median as the consensus. Then it runs a traffic light against your format: outdoor, marquee or indoor.
4. Wind and marquees: the risk almost nobody checks
Rain is annoying. Wind breaks things, starting with anything light: photocalls, banners, parasols, centrepieces, tablecloths, outdoor screens and poorly ballasted structures.
What we always do
- Check gusts, not average wind. A 15 km/h average with 45 km/h gusts is a different event.
- Get the marquee’s wind limit in writing from the installer, based on its certificate and anchoring (stakes, ballast, on grass or on stone).
- Check gusts during load-in too, not just during the event.
- Over-ballast when the forecast is uncertain.
Guideline thresholds (example, adjust to your case)
| Forecast gusts | What we would review |
|---|---|
| Below 30 km/h | Normal. Watch tablecloths and candles |
| 30 to 50 km/h | Remove light items, extra ballast, protect the photocall |
| 50 to 70 km/h | Talk to the installer about marquees and structures, plan B in motion |
| Above 70 km/h | Usually nothing light outdoors; the installer decides |
These are talking points for the briefing, not technical limits. The real limit of each structure comes from whoever makes or installs it.
5. Heat and cold: the other plan B
An outdoor event in July at 34 ºC in the shade at 1 pm can be worse than one in the rain. We prepare:
- Shade for guests at the ceremony and drinks, and the sun behind the guests, not in their eyes.
- Free, visible water from arrival, for crew and suppliers too.
- Timing: moving a ceremony one hour later changes a lot.
- In cold weather: patio heaters (approved by the venue), blankets, hot drinks and a sheltered area.
The Meteo Murphy traffic light also measures heat and cold against your format, with concrete suggestions such as shade and water for the crew.
6. Sunset and golden hour
- Golden hour: roughly the last hour before sunset. Warm, low light that photographers love.
- Blue hour: a few minutes after sunset. Deep blue sky, ideal with the venue lights on.
- Work out the exact sunset time for your date and location. In southern Europe it shifts by more than three hours between December and June.
- Check cloud cover in that slot: high cloud can give the best sky of the year; a low layer kills golden hour.
- Plan artificial light for when the sun goes: festoons, ambient lighting and, above all, safety lighting on paths and steps.
Put sunset as a cue in the run of show: couple portraits, toast or lights on, so the stage manager has it in view.
7. How to tell the client
The client checks five apps a day and each says something different. Your job is to provide calm with data.
- Agree the decision rule and date from the start. Example: “Thursday at noon we check the model consensus. If forecast rain in the 6 to 9 pm slot exceeds X mm or gusts exceed Y km/h, we switch to plan B”.
- Send short, regular updates, not a message every time an app changes.
- Talk about time slots and probabilities, not certainties.
- Separate data from recommendation: “This is what the models say. This is what we would do”.
- Record the decision in writing, with time and name.
Meteo Murphy writes the client report as text ready for WhatsApp or email, and if you save the event it alerts you on your phone when the weather changes.
Sample update (adapt it)
“Forecast for Saturday, 6 to 11 pm at the estate: most models show mostly clear skies and gusts below 25 km/h. History for that week is dry. We stay with plan A outdoors. We will review again on Thursday at noon as agreed.”
8. Common mistakes
- Relying on a single app.
- Deciding too early for no reason, or too late when there is no marquee left.
- Not agreeing who decides, so the client hears it from the photographer.
- Forgetting wind because “it is not raining”.
- Checking the city, not the venue.
Your next step
- Write plan B with cost, deadline and decision maker.
- Add it as an optional line in the budget.
- Check that week’s history for that place.
- Get each structure’s wind limit from the installer.
- Agree the rule and decision time (72 to 48 h) with the client.
- Work out sunset and add it to the run of show.
- Save the event in Meteo Murphy to get alerts if the weather changes.
It is free and needs no signup: enter the venue and time slot, and in a minute you will know whether it is time to start talking about plan B.
Frequently asked questions
When should you call the rain plan?
The main call is 72 to 48 hours out, when the forecast becomes genuinely useful. But plan B must be budgeted and booked long before, with an agreed date to confirm or release it with the supplier.
What does a 40 % chance of rain mean?
That in similar conditions it rains in that area and time slot roughly 4 times out of 10. It does not say how much: always read it alongside millimetres per hour and what the different models say.
How much wind is dangerous for a marquee?
It depends on the marquee and how it is anchored. The limit comes from the manufacturer or installer certificate: get it in writing and decide on forecast gusts, not average wind.
Is checking the weather three weeks out any use?
Not to know whether it will rain that day. It is useful to know what that week is usually like in that place and whether to book plan B: that is where climate history leads.
Is there a free weather tool for events?
Meteo Murphy is free with no signup: enter the venue and time slot, it combines the major weather models with 20 years of history and gives you a traffic light for your format.