I've travelled through extremes of temperatures on this journey but none more so than the other day in Baja California, Mexico. Although I had packed light for the trip down from LA, I had included my cashmere stuff from Mongolia and how glad I was. Crossing the Central Desert of Baja I think we must have been at a bit of altitude as it felt quite cold. I gradually added to the clothing I was wearing until I had six layers under my bike jacket (in Siberia it was seven) and I had my thermal balaclava on. And yet mid-afternoon, we reached the sea of Cortez and it was hot, so hot in fact that almost all of the layers were removed and I ended up down to my bikini to cool down by having a swim in the sea.