---
title: "California Mobile Signal Quality Map"
url: "https://wherobots.com/solutions/communication-service-providers/california-signal-quality-map/"
description: "Where California mobile service is slow and why: 79.9% of slow areas near a tower have a clear line of sight, a capacity problem. Built on Wherobots."
published: "2026-10-12"
modified: "2026-10-12"
---

# California Mobile Signal Quality Map

Signal quality

## California Mobile Signal Quality Map

Where mobile service in California is slow, and why. Wherobots joined Ookla speed tests with towers, terrain and tree canopy to separate slow areas with a clear line of sight to a tower, a capacity problem, from areas where hills or trees block the signal.

[Open the full map](https://wherobots.com/solutions/communication-service-providers/ca-telco-app/?view=app) [Talk to our team](https://wherobots.com/contact/?loc=california-signal-quality-map-hero)

2,854

slow areas within 2 km of a tower

79.9%

of those have a clear line of sight

1.51M

people in capacity-limited areas

***Los Angeles basin, California** Share of measured service that is underserved*

under 10% 10-25% 25-50% 50-75% 75% or more not measured

Of 2,854 slow areas within 2 km of a tower, 2,281 (79.9%) have a clear line of sight: a capacity problem.

Speed tests: Ookla Open Data. Towers and buildings: Overture Maps. Terrain: Copernicus. Canopy: Meta. Population: US Census ACS. Analysis: Wherobots. Basemap: OpenFreeMap, OpenMapTiles, OpenStreetMap contributors.

## How the map is built

### Measure service

Ookla speed tests cover 48,999 map tiles and 231,828 tests across California. 6,664 of those tiles (13.6%) are underserved.

![](https://wherobots.com/wp-content/themes/wherobots/blocks/cards-grid/img/mask.svg)

### Find the nearest tower

Slow areas within 2 km of an Overture Maps tower are the near-tower set, where tower distance does not explain the slow service.

![](https://wherobots.com/wp-content/themes/wherobots/blocks/cards-grid/img/mask.svg)

### Check the line of sight

A modeled sightline over terrain and tree canopy splits slow areas into capacity-limited, terrain-blocked and foliage-blocked.

![](https://wherobots.com/wp-content/themes/wherobots/blocks/cards-grid/img/mask.svg)

### Count the people

US Census ACS estimates give the population of each kind of slow area. Capacity-limited areas hold 1.51 million people.

![](https://wherobots.com/wp-content/themes/wherobots/blocks/cards-grid/img/mask.svg)

FAQ

## California signal quality map FAQ

### Why is most bad service a capacity problem?

Of the 2,854 slow areas within 2 km of a tower, 2,281 (79.9%) have a clear line of sight to it. The signal reaches them, so the limit is network capacity.

### Why are many hexagons grey?

Only 8,872 of the 78,109 hexagons have a speed test. Grey means not measured, never zero, so every underserved count on the map is a floor.

### Is the line-of-sight check a speed prediction?

No. It is a modeled sightline screen over terrain and tree canopy that sorts slow areas by likely cause.

### Where does the data come from?

Ookla Open Data speed tests, Overture Maps towers and buildings, Copernicus terrain, Meta canopy height and US Census ACS population estimates.

### What did Wherobots compute?

Wherobots joined the speed tests to the nearest towers, ran the line-of-sight checks over terrain and canopy, and counted the people in each slow area.

## Find your capacity gaps

Tell us about your network, and we will walk you through the analysis on your markets.

[Talk to our team](https://wherobots.com/contact/?loc=california-signal-quality-map-cta)

![](https://wherobots.com/wp-content/themes/wherobots/blocks/cta-banner/img/figure.svg)