If you're walking from Konstanz to Genève on the Vía Jacobi in September, expect a mix of warm and cool weather. The temperature at the start of the journey will average around 20°C and will gradually drop to 15°C as you near Gland. After that, it again rises to about 20°C in Genève. Temperatures could also drop to as low as 2°C in places like Einsiedeln.
You should also prepare for some rain. It could be a light drizzle or heavy rainfall. Some areas like Einsiedeln and Buochs may have more rain than places like Märstetten, Rapperswil, and Brunnen.
Some areas like Konstanz, Märstetten, and Fischingen could have a mix of sunny and rainy weather. Similarly, southern areas like Saint-Prex and Gland may also have both sunny and rainy days. As you get closer to Genève, you're more likely to have sunny days. But be prepared for sudden changes in weather, especially between day and night. So make sure you're ready for all kinds of weather in this journey.
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