Does Weather Affect GNSS Positioning Accuracy?

When GNSS positioning performance degrades, one of the first questions asked is always: “Is it because of the weather?”

Rain, clouds, fog, or snow are frequently blamed for unstable positioning. But in reality, weather itself has very little impact on GNSS accuracy. So what actually causes positioning issues? And why does GNSS sometimes seem less reliable during rainy or overcast conditions? 

Understanding how GNSS signals travel through the atmosphere helps clarify this common misconception.

The Short Answer: Weather Has Minimal Impact on GNSS

Normal weather-sunny, cloudy, or rainy-does not significantly affect GNSS positioning. GNSS signals are engineered to penetrate the atmosphere reliably. When positioning quality drops in bad weather, the issue is almost always environmental or installation-related, not the weather itself.

Why Weather Has Little Effect on GNSS Signals

GNSS satellites transmit signals in the L-band (1.1GHZ–1.6 GHz), which is specifically chosen for its ability to:

• Penetrating clouds, rain, fog, and snow with minimal attenuation
• Maintaining stable long-distance propagation
• Remaining insensitive to precipitation compared to optical or radar sensors

As a result, sunny, cloudy, rainy, or snowy conditions behave almost identically from a GNSS signal propagation perspective.

In other words, normal weather rarely interferes with GPS or GNSS positioning.

When Weather Seems to Affect GNSS

Although the weather itself does not degrade GNSS signals, it can indirectly influence the surrounding environment, leading to positioning issues:

1. Signal Blockage

Buildings, terrain, vehicles, and vegetation obstruct satellite signals. Wet foliage or dense surroundings can slightly increase attenuation.

2. Multipath Effects

Rain can increase reflections from wet roads, building surfaces, and metallic structures. Reflected signals interfere with direct signals, causing position jitter or drift.

3. Antenna and Installation Issues

Snow or ice accumulation on the antenna, water intrusion into connectors, poor grounding, or limited sky view can significantly degrade performance.

4. Interference and Noise

Bad weather may coincide with increased electrical activity or the operation of nearby equipment, introducing RF noise that affects GNSS reception.

The Role of the Ionosphere

While ground-level weather has minimal influence on GNSS, signals must still pass through the ionosphere, a layer of the upper atmosphere filled with charged particles.

Variations in the ionosphere—primarily driven by solar activity, time of day, and geographic location—can introduce small timing delays in GNSS signals.

Modern multi-frequency GNSS receivers are designed to correct most ionospheric errors, allowing for highly accurate positioning even under varying atmospheric conditions.

Importantly, these ionospheric effects are not related to rain, clouds, or snow.

Practical Takeaway

If GNSS performance degrades during bad weather, improvement is unlikely to occur simply by waiting for clearer weather. Instead, focus on:

• Proper antenna selection and placement
• Clear sky visibility
• Multipath mitigation
• Robust system and installation design

GNSS accuracy depends far more on the environment and system design than on the weather itself.

Qtalis’ GNSS receivers and antennas feature strong anti-interference and multipath mitigation capabilities, ensuring reliable performance even in harsh environments.

📘 Recommended Reading

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