Everyone knows how frustrating it is to plan your week around a forecast, only for it to be inaccurate. So, what factors can you look out for, and what are the most reliable forecasts?

Introduction to Weather Forecasting

Like any science, weather forecasting can be a bit overwhelming to get into. Having a basic understanding of how it works will help you understand its limitations, as well as what factors significantly improve your forecast reliability.

At its most basic, weather forecasting is like any other scientific process. It involves data collection, analysis of trends, and coming up with a conclusion as to what you think the weather will likely do next.[1]

To begin with, data is collected from a range of sources on the ground, in the air, and even out to sea. This data includes current weather conditions, atmospheric pressures, wind speeds, and many more factors.[2]

All of this data is then compiled for a given location in a weather center, where high processing capacity computers can look at all the information and predict how the weather will evolve.[2]

As climate change creates new and unseen weather patterns, weather prediction may become more difficult.

This is known as modeling, and uses complex math in order to simulate what the weather is likely to look like over time. There are trillions of calculations done, at incredible speeds, in order to determine the most likely outcome for the weather.

There are many different weather models covering different parts of the world. Some predict the weather for any point on the globe, such as GFS, ECMWF, or ICON. Others, like NAM or HRRR, specialize in certain regions and offer higher resolution, i.e. finer and usually better forecasts.[3]

It is worth noting that as climate change creates new and unseen weather patterns, weather prediction might become more difficult. The current system is based on years of collected data, so when new conditions arise, the weather models may need to be adjusted, or other measures may be required in order for forecasting to stay reliable.


What Makes a Reliable Forecast?

Factors to keep in mind for people without a meteorological background

If you aren’t a meteorologist, finding a reliable weather forecast can be difficult, especially if you aren't sure what to look for. Here’s a list of tips and tricks to find a reliable forecast:

  • Look for your specific location [4] – Forecasts are based on local data, so the closer you can hone in on your location, the more likely your forecast will be accurate.
  • Check your forecast as close as possible to the time [4] – As weather patterns change and evolve, the forecast will change. Looking at the time you need to leave the house can help ensure you have an accurate forecast.
  • Make sure your forecast uses reliable data – A good starting point is knowing which model a forecast is based on. E.g. ECMWF and GFS are considered to be the most reliable models when it comes to global forecasts. If a weather forecast uses data from either of these models the chances of getting reliable results is quite high. If you aren’t sure how your forecast is generated, look for one that is used by meteorologists or endorsed by them.

Limitations of weather forecasts

Weather is complicated and difficult to forecast correctly (sometimes to our dismay). Here are some of the limitations of weather forecasts[5]:

  • Depending on the terrain and environment in which a location is located, forecast reliability varies, sometimes significantly. For example, mountainous areas tend to be more difficult to forecast because mountains act as barriers to clouds, air, and even the sun. They can greatly affect how the weather develops, making it more difficult for weather models to calculate reliable forecasts.
  • Weather forecasts rely on existing data – As I have already mentioned, weather forecasting requires that we have observed those atmospheric conditions before. As climate change influences weather and atmospheric conditions, we begin to move into uncharted, unpredictable waters.
  • Limited time frame – Weather forecasts can only be made for a certain period of time before they become unreliable.


Why 14-day forecasts are unreliable

One of the biggest limitations of a forecast is the length of time we have before a forecast becomes unreliable. A five-day forecast is reliable about 90% of the time, while a seven-day forecast is reliable about 80% of the time. But a ten-day forecast is only reliable about 50% of the time.[6]

This is because of the butterfly effect. This term describes the idea that small changes can snowball into large effects, which is also the case for the weather. Small changes in the atmosphere, rainfall, humidity, or any number of other factors can cause large changes in the weather conditions in the coming days. This is why 14-day forecasts are so difficult and should generally be taken with a grain of salt.[7]

The general rule of thumb: The closer to the date, the better the forecast.

Why Sonuby?

Choosing a forecast that works for you isn’t as easy as one might think. There are tons of resources like apps and websites available and choosing “the right one” may be quite tricky. Especially if you are not familiar with reliable forecast providers.

This is why I teamed up with meteoblue, a Swiss based weather data provider known for their unique expertise in weather forecasting.

meteoblue uses a variety of weather models such as ECMWF, GFS and ICON and combines them into its own model. Intelligent post-processing of each model enables them to deliver one of the most reliable forecasts available.

These forecasts are available for any location on the planet which makes meteoblue the perfect data provider for Sonuby.

I can’t wait to hear what your experience will be!




[2] https://gargicollege.in/wp-content/uploads/2020/03/weather_forecast.pdf

[3] https://weather.us/model-charts#:~:text=Global%20models%20with%20worldwide%20weather%20forecasts&text=These%20models%20are%20all%20generally,the%20US's%20GFS%20slightly%20behind.  


[5] https://geographypoint.com/2022/08/7-disadvantages-of-weather-forecasting/

[6] https://scijinks.gov/forecast-reliability/

[7] https://indianapublicmedia.org/amomentofscience/limitations-weather-forecasts.php

This post is part of Sonuby's Weather Wednesdays series, where we discover exciting weather phenomena and interesting facts about the weather. Subscribe to our newsletter to receive posts like this one in your inbox.

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