In any marathon or outdoors sporting event, the weather conditions will always have a huge impact. Temperature interacts with the humidity, which makes it harder to sweat and makes it harder for the athlete to stay cool.

Any rain at all, meanwhile, will add water and weight to clothing and footwear, draining energy faster; and running into the wind, or even being buffeted by variable wind adds drag and slows the runner.

The weather team had to work on three different forecasts, each relevant at different times.

The first decision was deciding the moment when Eliud should travel to Vienna. This required the team to identify a period of the right weather in advance of the event.

The second decision was to pick the day for the event. This decision had to be made 72 hours in advance and would determine when Eliud entered his final tapering phase.

The final decision, made the day before the Challenge, was to identify the precise two-hour window for optimal conditions on the day.

These decisions pushed limits of forecasting technology.

Vienna was eventually chosen as the venue for the challenge because it offered the best chance of getting the right environmental conditions — along with other parameters like time zone and altitude.

The tree lined course was a major factor in the decision as it reduced the unpredictability of one of the most unpredictable of the six parameters — the wind.

The INEOS 1:59 Performance Team had all the equipment built, shipped to Vienna and installed.

These sensors as well as modelling from historical data gave them a much greater understanding of what the macro-scale conditions would be on the course on the day, which allowed them to forecast and make the big three calls on travel date, race date and time.

All the hard work paid off, with the very best forecasting technology, the team were able to make the big calls with as much certainty as anyone could and with a little bit of luck and help from mother nature the optimal weather conditions were achieved helping Eliud to make history on 12th October 2019 at 10.14.59.40.2 CET