Sa Pa sits at about 1,600 m, so it is cool all year, but each season looks different:
- December – February (winter): cold, usually 5–10°C, some nights near 0°C; some years bring frost or snow on Fansipan and O Quy Ho Pass. Good for cloud-watching, but many foggy days.
- March – April (spring): warming up, with peach, plum and pear blossoms; little rain, easy hiking.
- Late April – May: water season, when flooded rice terraces mirror the sky; excellent for photos.
- June – August (summer): green rice, much cooler than Hanoi, but frequent rain, slippery trails and landslide risk.
- Mid-September – early October: golden harvest season, the busiest time.
- October – November: dry and cool (around 18–22°C by day) with clear skies; great for trekking and cloud views.
Note: mountain weather changes fast; sun, rain and fog can all happen in one day. Avoid weekends and public holidays if you want quieter trails.