On Sunday (2023-09-24), the Berlin Marathon will take place. It is one of the biggest marathons in the world with more than 45’000 runners. Besides running, there are more competitions like an inline skating marathon. We checked the weather during the last 20 years to see if it correlates with this year's weather forecast for Berlin. For this, we used historical weather simulation data from history+, our interactive data downloading interface with multiple data ananylsis tools, and access to past weather data since 1940. Specifically, we analysed the weather conditions over the past years since 2003 for the time period between 20 September and 30 September using the ERA5T reanalysis weather model. We considered the most essential weather variables for running, which are temperature, precipitation, sunshine duration and wind speed.
The average daily temperatures for each year can be seen in the first diagram. The average temperature of all years is 13.5°C, ranging from a maximum of 18°C in 2006 to a minimum of 10.7°C in 2022. Generally, moderate temperatures at the end of September are observed, which are pleasant for running. This year's forecast predicts 13°C in the forenoon, reaching 17°C at noon and in the afternoon. Thus, these values are in the range of the last 20 years.
The blue columns in the second chart show the absolute maximum precipitation amount on a single day between September 20th and September 30th. This ranges between nearly no precipitation (lowest: 0.5mm in 2016) to moderate precipitation (highest: 28.4mm in 2020). Out of 220 days analysed, it only rained on 96 days, equivalent to around 44% out of all days. This year, on 24th September, no precipitation is expected, as the predicted precipitation probability is 0%, and the forecast itself has high predictability.
Next, the average daily sunshine duration was analysed. Most years, there were between 5 and 7.5 hours of sunshine daily. This year, 7 hours of sunshine are expected, corresponding to the average.
The last variable analysed was the average daily wind speed. Wind can affect how fast we run; if there is a backwind, you get wind support, and therefore it is easier to run faster. Conversely, with headwinds, running becomes more challenging. The average daily wind speed in the last 20 years was between 6 and 10 km/h. That is quite low, which means good conditions for running. This year, stronger winds are anticipated, on average 16 km/h, but it is expected to decrease in the afternoon. This value is above average as compared to the last years.
Overall, the forecast for Berlin this Sunday shows partial correspondence with the historical weather data. The highest difference from the last years is expected in wind speed, as we forecast above-average values. However, the weather conditions seem to be perfect for running.
meteoblue wishes all competitors a successful marathon!