For allergy sufferers, climate matters. Dry climates with low humidity tend to have lower mold and dust mite populations. Mild winters mean less time spent indoors breathing recirculated air. Moderate temperatures reduce the intensity of pollen seasons. We built a climate-based allergy comfort index to identify the counties most likely to provide relief.
This index is a proxy based on climate data, not pollen counts. Individual allergy triggers vary, but these counties offer the most favorable climatic conditions for reducing common airborne allergens.
The 25 Best Counties for Allergy Sufferers
Orange County, CA scores highest on our allergy comfort index with a score of 89.7. These counties combine dry air, moderate temperatures, and minimal snowfall that together reduce common allergy triggers.
| Rank | County | State | Allergy Score | Avg Temp (°F) | Precip (in) | Snowfall (in) |
|---|---|---|---|---|---|---|
| 1 | Orange County | CA | 89.7 | 65.2875 | 12.298749999999998 | 0 |
| 2 | Ventura County | CA | 89.3 | 61.333333333333336 | 15.182857142857143 | 0.03333333333333333 |
| 3 | San Francisco County | CA | 86.7 | 56.900000000000006 | 21.765 | 0 |
| 4 | Alameda County | CA | 86.5 | 59.87777777777779 | 18.112000000000002 | 0 |
| 5 | San Benito County | CA | 86.4 | 58.23333333333333 | 13.58 | 0.06666666666666667 |
| 6 | San Diego County | CA | 86.2 | 62.621428571428574 | 14.016206896551724 | 3.75 |
| 7 | Monterey County | CA | 86 | 57.71111111111111 | 19.940000000000005 | 0.04285714285714286 |
| 8 | Canyon County | ID | 85.4 | 52 | 10.33 | 10.6 |
| 9 | Apache County | AZ | 85.3 | 51.44166666666667 | 11.938888888888888 | 12.22 |
| 10 | Los Angeles County | CA | 85.3 | 63.73076923076922 | 16.065384615384612 | 0.0888888888888889 |
| 11 | Santa Barbara County | CA | 85 | 59.71111111111112 | 18.752499999999994 | 0 |
| 12 | San Luis Obispo County | CA | 84.4 | 59.77142857142858 | 20.653333333333332 | 0.014285714285714287 |
| 13 | Contra Costa County | CA | 84.3 | 60.38333333333333 | 19.37333333333333 | 0.13999999999999999 |
| 14 | Santa Clara County | CA | 84.3 | 59.0875 | 21.20875 | 3.62 |
| 15 | Stanislaus County | CA | 84.1 | 63.55 | 12.33 | 0 |
| 16 | Nez Perce County | ID | 84.1 | 53.8 | 12.87 | 12.7 |
| 17 | Merced County | CA | 84 | 62.800000000000004 | 10.37875 | 0.016666666666666666 |
| 18 | Kern County | CA | 83.9 | 62.96923076923077 | 8.632 | 1.2545454545454544 |
| 19 | Kings County | CA | 83.7 | 63.65999999999999 | 7.835000000000001 | 0 |
| 20 | San Mateo County | CA | 83.4 | 57.550000000000004 | 25.394 | 0 |
| 21 | Lassen County | CA | 82.9 | 50.25 | 12.936666666666667 | 21.05 |
| 22 | San Joaquin County | CA | 82.1 | 62.525 | 15.928 | 0 |
| 23 | Cochise County | AZ | 81.5 | 61.7875 | 14.30529411764706 | 1.7307692307692304 |
| 24 | Santa Cruz County | AZ | 81.2 | 61.660000000000004 | 16.133333333333336 | 0.3666666666666667 |
| 25 | Inyo County | CA | 81.2 | 66.64 | 7.673333333333334 | 0 |
Methodology
The allergy comfort index is a weighted composite of four climate factors: dryness (30% — lower precipitation is better), temperature moderation (30% — proximity to 60°F annual average), low snowfall (20% — less mold potential), and low extreme heat (20% — fewer ozone and dust events). All data comes from NOAA Climate Normals 1991-2020. This is a climate proxy, not a medical recommendation.
Data source: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991-2020. All figures represent 30-year averages and may differ from individual-year observations. Station-level data is aggregated to county level using spatial averaging.