Verizon currently ranks first for coverage in this area, with a coverage score of 96.3. Compare Wireless Carriers uses FCC broadband map data to estimate and calculate coverage scores. More on that further below.Coverage rankings for Napa, CA
| Rank | Carrier | Score | Overall | 4G LTE | 5G | Fast 5G | Average Signal |
|---|---|---|---|---|---|---|---|
| 1 | Verizon | 96.3 | 100.0% | 100.0% | 95.0% | 85.8% | -88 dBm |
| 2 | T-Mobile | 96.3 | 100.0% | 100.0% | 93.6% | 84.6% | -86 dBm |
| 3 | AT&T | 85.5 | 97.9% | 97.9% | 94.8% | 59.8% | -107 dBm |
Scores include coverage area, network type, and average signal strength.
Cell phone coverage map for Napa, CA
Zoom in for local detail. Tap or click a colored area to see coverage and signal details. On mobile, use two fingers to move the map.
Map data © OpenStreetMap contributors, © CARTO. Rendered with MapLibre. FCC BDC mobile coverage processed by Compare Wireless Carriers.
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Cell phone coverage by network in Napa, CA
Verizon
- Overall
- 100.0%
- 4G LTE
- 100.0%
- 5G
- 95.0%
- Fast 5G
- 85.8%
T-Mobile
- Overall
- 100.0%
- 4G LTE
- 100.0%
- 5G
- 93.6%
- Fast 5G
- 84.6%
AT&T
- Overall
- 97.9%
- 4G LTE
- 97.9%
- 5G
- 94.8%
- Fast 5G
- 59.8%
County coverage is shown for surrounding-area context and uses land-area only coverage.
Coverage varies by neighborhood. Your carrier shouldn’t.
US Mobile lets you switch between all three major networks, so you can choose the one that works best where you actually use your phone.
Pricing, network access, switching terms, and home internet availability may vary.
Coverage by ZIP code in Napa, CA
ZIP code areas can extend beyond city limits, so this table is best used for local comparison around the city.
| ZIP Code | AT&T | T-Mobile | Verizon |
|---|---|---|---|
| 94503 | 90.6% 90.4% 73.8% 50.9% -111 dBm | 88.1% 87.0% 77.6% 64.7% -88 dBm | 99.8% 99.8% 89.9% 79.7% -88 dBm |
| 94558 | 64.4% 64.2% 42.5% 26.9% -115 dBm | 55.3% 54.9% 31.3% 19.5% -95 dBm | 87.4% 87.3% 34.2% 21.4% -98 dBm |
| 94559 | 88.9% 88.7% 79.4% 39.2% -114 dBm | 87.4% 86.9% 83.0% 66.4% -89 dBm | 99.8% 99.8% 88.3% 69.2% -92 dBm |
About The Coverage Data
Coverage and signal estimates are derived by Compare Wireless Carriers from carrier-reported data in the FCC’s National Broadband Coverage Map, last updated in June 2025. “Percent covered” shows how much of the city or ZIP code area has a carrier signal, whether weak or strong. Signal bars show the estimated average signal strength in areas of Napa, CA where that carrier has coverage.
If a carrier says you should have service but you do not, run a challenge test with the FCC Mobile Speed Test App. The FCC uses those results to check carrier-submitted coverage data and requires a carrier response when enough tests show a pattern of inaccurate coverage reporting.