Errachidia sits at the edge of the Sahara, which means summers are fierce — July and August regularly hit 40°C and above, and the Ziz Valley absorbs heat all day long. Spring (March to May) and autumn (September to November) are the best times to visit: warm enough for the desert but cool enough to walk comfortably. The light is also better in these seasons, with clear skies and long afternoons.
Winter brings cold nights at this altitude — temperatures can drop below freezing after dark in December and January — but days are sunny and the skies are the clearest of the year. Snow occasionally falls on the passes above town, occasionally blocking the N13 from Midelt for a day or two.
The desert south of Errachidia receives almost no rain, but occasional storms over the Atlas can send flash floods down the Ziz Valley with little warning. If you are camping near a dry riverbed, keep this in mind between October and April.