There are a number of aspects that affect the quality of the forecast for your specific location.
- Your location may not be close to a forecast grid point.
Forecast models use a grid system to approximate forecasts for individual locations. The shape of the grid and the distance between grid points can vary, but the further away your location is from a grid point the more approximation will be required to deliver a forecast.
- Local terrain and topography can impact forecasts.
Weather predictions are also impacted by local variations in terrain and topography, creating microclimates that differ from the larger surrounding area. Coastlines, mountains and valleys are common examples that provide a challenge for grid-based forecasts.
- Convective weather can introduce short term forecast volatility.
Convective weather refers to the upward/vertical movement of air that can lead to complex, rapidly developing weather systems. This can create volatility in short term conditions and as a result, small variations in the forecast can lead to larger inaccuracies for your location.