How to Read a Weather Forecast Before You Camp

“Partly cloudy, 40 percent” sounds like useful information. It does not say whether to pack a tarp, move your tent, or skip the second night. Most first-time campers check the weather once, glance at an icon, and stop there. The forecast has more to offer, and the National Weather Service (NWS) publishes it for free.

This article shows how to read the NWS forecast for the exact spot where you will camp. You will learn what the chance of rain measures, where to find wind and the overnight low, what watch, warning and advisory mean, and when to check again.

One limit up front. This text does not teach you what to do in a storm, in extreme heat or in cold. The NWS safety pages cover those hazards, and they are listed under sources. The job here is smaller: use the forecast to decide what to bring, where to pitch and when to change plans.

Start with a forecast for your campsite, not your city

On weather.gov you can search a city, state or ZIP code, or click the map to set the exact forecast point. A park can cover a lot of ground, so click as close to your campground as you can.

The point forecast page shows several things worth a look:

A day-by-day list with a high for each day and a low for each night.
A detailed text forecast with wind speed, direction and gusts.
Links to an hourly forecast and to the Forecast Discussion, a note written by the forecasters.
An “About this forecast” box with the forecast point, its elevation, and the time of the last update.

Compare the elevation in that box with the elevation of your campground. If they differ by a lot, treat the temperature numbers as a rough guide and ask a ranger or camp host. NPS suggests exactly that on arrival: talk to a ranger or campsite host about rain, wind, snow or extreme temperatures that could affect your plans.

What the numbers mean

Forecast item	What it tells you	What to do with it
Chance of rain	The probability that the forecast point gets at least 0.01 inch (0.25 mm) of rain in that time period	Use it with the rest of the text. It says nothing about how heavy the rain will be
Wind and gusts	Speed range, direction, and the highest gusts expected	Check stakes and guy lines. Look up for dead branches over your site
Overnight low	The coldest expected temperature for each night period	Plan your sleep system and layers around it

Chance of rain

NWS defines probability of precipitation as the chance that the forecast point gets at least 0.01 inch (0.25 mm) of rain. The definition sets only a minimum amount, so the number says nothing about how heavy or how long the rain will be. Read the sky words and the time of day next to it.

Wind

NWS says that when winds are sustained at 40 to 50 mph (64 to 80 km/h), isolated wind damage is possible, and higher speeds can cause widespread damage. The forecast cannot tell you your tent’s limit. Your tent’s instructions can. NPS also advises looking up when you pick a site: if you see dead branches overhead, do not camp under them. See how to pitch a tent for staking basics.

Lightning

NWS says no place outside is safe when thunderstorms are in the area, and if you hear thunder, lightning is close enough to strike. Its safe shelter list has two items: a substantial building with electricity or plumbing, or an enclosed, metal-topped vehicle with the windows up. A tent is not on that list. NWS says to stay in shelter at least 30 minutes after the last thunder. If thunderstorms are in your forecast, find the nearest building or your parked car before dinner.

Watches, warnings and advisories

NWS uses three words for hazardous weather, and they are not interchangeable.

Advisory: a less serious condition. NWS says it may cause significant inconvenience and, if caution is not used, could lead to situations that threaten life or property. Dense fog and frost advisories are examples.
Watch: conditions are favorable for a hazard, but whether, where and when it happens is still uncertain. A High Wind Watch works this way.
Warning: the hazard is happening, imminent or highly likely, and it threatens life and property. A Flash Flood Warning is issued when flash flooding is in progress, imminent or highly likely.

NWS gives a short rule for flooding: a watch means be prepared, a warning means take action. It also notes that a flash flood can happen in places that are not getting rain at the moment. That matters if your campsite sits low or near a stream. NPS lists ravines that might flood among the places to avoid, and it warns that low, sunken ground gets very wet in rain.

The thresholds behind these alerts are set locally. The NWS glossary says, for example, that the criteria for an Extreme Heat Warning vary from place to place. Do not memorize a number from a different state. Read the alert text for your county.

When to check again

The forecast changes, so treat it as a schedule, not a one-time task.

When you book, to choose the right gear and the right dates.
The night before you leave, to pack the rain layer or the extra blanket.
At the campground, by asking a ranger or camp host. NPS says that if you cannot reach one, check a local newspaper, a weather website or a radio station.
Each morning and evening, because NPS reminds campers to keep an eye on the sky and prepare for changing conditions.

Cell service can disappear near the campground, so write the key numbers on your checklist before you leave town.

Common mistakes

Reading the forecast for a nearby city. Use the point forecast near the campground.
Reading only the daytime high. The overnight low decides how you sleep.
Treating a low rain chance as a dry night. The percentage is not a rain amount.
Mixing up watch and warning. A watch is a prompt to get ready. A warning is a prompt to act.
Checking once. A forecast made for day one may not hold on day three. See off-season camping for trips where weather swings are larger.

Frequently asked questions

Where should you get a camping forecast?

Use weather.gov, the National Weather Service site, and set the forecast point near your campground. Add what the park or campground says in its alerts and from rangers.

What does a 30 percent chance of rain mean?

NWS defines it as a 30 percent probability that the forecast point receives at least 0.01 inch (0.25 mm) of rain in that time period. It does not describe how long or how hard the rain will be.

What is the difference between a watch and a warning?

A watch means conditions are favorable but not certain. A warning means the hazard is in progress, imminent or highly likely. Local NWS offices set their own criteria for many alerts.

How do you plan for a forecast that keeps changing?

Pack for the range, not the average, and keep a backup plan. NPS says not to push on if conditions turn unsafe: you can reschedule or choose another activity. A layering plan helps with temperature swings.

Next step: add a forecast check to your plan

Put three lines in your Planner: the date you will first check the forecast, the date you will check it again, and the backup plan if an alert appears. Then write the NWS alert name next to each trip day, so you know what to look for.