Climate twins of Portola Valley, CA
These are the US cities whose 12-month climate pattern most closely matches Portola Valley's. Each "twin" must be at least 140 miles away to avoid trivial near-neighbor matches. Similarity is computed across all 24 monthly metrics (12 average temperatures + 12 average precipitations), normalized so temperature and precipitation contribute equally.
Side-by-side: Portola Valley vs its climate twin
Top match: Rio Dell, CA
| Month | Portola Valley | Rio Dell | ||||
|---|---|---|---|---|---|---|
| High | Low | Precip | High | Low | Precip | |
| January | 54.7°F | 40.9°F | 7.77 in | 56.6°F | 42.6°F | 8.59 in |
| February | 55.1°F | 40.3°F | 7.97 in | 57.8°F | 42.7°F | 7.83 in |
| March | 58.4°F | 41.3°F | 6.32 in | 59.2°F | 43.5°F | 6.93 in |
| April | 61.6°F | 42.6°F | 3.37 in | 61.6°F | 45.2°F | 3.89 in |
| May | 66.9°F | 47.2°F | 1.29 in | 64.4°F | 48.6°F | 1.91 in |
| June | 75.2°F | 52.0°F | 0.42 in | 67.2°F | 51.4°F | 0.57 in |
| July | 80.6°F | 57.7°F | 0.04 in | 70.0°F | 53.5°F | 0.14 in |
| August | 80.9°F | 58.5°F | 0.11 in | 71.6°F | 54.2°F | 0.05 in |
| September | 78.9°F | 57.1°F | 0.18 in | 72.5°F | 51.9°F | 0.47 in |
| October | 71.0°F | 51.7°F | 1.73 in | 68.6°F | 48.3°F | 2.38 in |
| November | 60.4°F | 44.4°F | 4.60 in | 60.6°F | 44.9°F | 5.23 in |
| December | 53.8°F | 40.1°F | 8.41 in | 55.1°F | 41.6°F | 9.68 in |
Cities that consider Portola Valley their climate twin
These US cities have Portola Valley in their top 3 most-similar list — meaning if you were to move from any of these places, Portola Valley would feel familiar.
- Ferndale, CA (ranks Portola Valley #1)
- Fortuna, CA (ranks Portola Valley #1)
- Rio Dell, CA (ranks Portola Valley #1)
- Willits, CA (ranks Portola Valley #1)
How this is computed
Each city is represented by a 24-dimensional vector: 12 monthly average temperatures and 12 monthly average precipitations. Each dimension is z-score normalized across the population of US cities, so that temperature variance and precipitation variance contribute proportionally. Distance between cities is Euclidean. We filter out cities within 2° latitude/longitude (~140 miles) so that "twins" mean climatically similar but geographically distinct — not just the neighboring town. Full methodology →