The air is then forced down the mountain slopes out towards the Pacific coast; the air mass is further heated by compression as it drops in altitude before reaching the Los Angeles Basin, western San Diego County and Tijuana (Baja California) at typical speeds of 35 knots. The southern California coastal region gets some of its hottest weather of the year during autumn while Santa Ana winds are blowing. During Santa Ana conditions it is typically hotter along the coast than in the deserts and the humidity plummets to less than 15%.