Almería is one of the driest cities in Europe, and the light can be dazzling even in winter. Spring and autumn are the easiest seasons: warm enough for the coast, comfortable enough for the Alcazaba climb, and quieter than high summer.
July and August are hot, especially away from the sea breeze. Winter is mild and often clear, a good time for city sights and desert walks if you are not expecting a classic beach holiday.