Season
The Best Time of Year to Walk the Ruta de la Lana
The Lana crosses open, high, treeless country. That single fact decides your calendar more than anything else.
Late spring and early autumn
Mid-May to late June, and the whole of September, are the sweet spots: long light, manageable heat, water still running, fields green or gold rather than scorched. This is the season the guide is written for, and the one I'd choose every time.
High summer — possible, but respect it
July and August are walkable if you start at first light and you respect the sun. There is very little shade on the meseta, and on the high stages around the Sierra de Pela the vegetation is shorn close. Walk early, cover up, and carry more water than feels reasonable — by mid-morning half of it is already inside you.
Winter — read the rivers
Winter has a stark beauty, but two things bite. The Caracena canyon between Retortillo de Soria and Fresno de Caracena becomes impassable after heavy rain — the river swells, the fords turn dangerous. There is a marked detour, but ask in Retortillo about the last 48 hours of weather before you commit. And the cold high stages are exposed to a wind that doesn't forgive.