Whether you are deciding what to do for your weekend or planning a wedding, it helps to know when the weather forecast actually starts to come into focus.

Meteorologist Caitlin Kaiser explains the best ways to use the forecast to your advantage for event planning. 

Timeline

When you are looking at the forecast to make decisions seven to 10 days out, that is really just for overall trends and patterns, Kaiser explains. 

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“This is for direction and not detail,” she says. “Such as whether it will be wetter or warmer than normal.”

When you get to five days out, details start to come into focus and you can begin making solid plans. 

Two to three days is what she calls “the sweet spot” for most event planning, allowing for reliable short-term decisions. 

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At one day out, you can make firm decisions. The forecast is 96% to 98% accurate at that point.

Location

There is one big caveat to forecast accuracy: location. Some places have much more consistent and predictable weather, which makes their forecasts more accurate.

For example, the ocean acts as a giant thermal regulator for coastal regions, Kaiser explains. And in more arid, dry regions like the Southwest, the climate prevents more disruptive weather systems.

Meanwhile, the middle of the country lacks those moderating factors. In the U.S., cold air masses from Canada meet warm, moist air masses from the Gulf. This can cause huge temperature swings and the potential for storms that can throw off your plans.

Season

Predictability also depends on the season.

During the summer, there is a lot more moisture and warm air. That combination fuels notoriously hard-to-predict pop-up afternoon thunderstorms.

Fall is the most reliable season since severe storms are less intense and widespread compared to spring.

Winter could also be as reliable, but it is colder, so you have to take temperature into account.

Predictability 

Some aspects of the forecast are more difficult to pin down than others. 

Temperature is a little more reliable further out, but precipitation is notoriously difficult to predict, she says.

And a change in temperature by a few degrees likely won't change your entire plans, while rain easily could.

Forecast accuracy has come a long way since the '90s.

“A seven-day forecast now is similar to the accuracy of a three-day forecast back then,” Kaiser says.

Content writer Ada Wood enjoys exploring the stories that science and climate teach us about our natural world and how it influences the way we live in it.