The effect weather has on fuel consumption of motor vehicles

The question of fuel efficiency often becomes an extremely acute one for drivers, especially in European countries. High prices for gasoline, environmental pollution - these factors necessitate finding ways to tightly control the amount of fuel consumed. This is of particular relevance to companies engaged in large-scale freight transportation where fuel expenses are a significant part of transport costs, and their reduction can improve the company’s market competitiveness.

Fuel expenses depend on several overall factors: the weight of the vehicle, driving habits, road conditions, and the extra energy expended in certain kinds of weather, etc.

Bearing in mind that road conditions are also often determined by different weather events, it becomes clear that, when planning prolonged resource-consuming trips, attention paid to weather forecasts is not time wasted. And for road-haulage companies, having historical meteorological data for the entire transport route can be extremely useful for assessing the appropriateness of the amount of fuel used by the driver.

How Can Different Weather Events Affect Fuel Consumption?
Let’s examine only the major weather factors.

Temperature.
Cold weather and driving in wintry conditions can significantly increase a vehicle’s fuel usage.  Fuel efficiency tests show that in city conditions the difference in gasoline consumption between air temperatures of -7 °С and +25 °С can reach 12%. And on short trips (up to 5-7 km), this figure can increase to 22%. For hybrid vehicles, the situation is even worse. Their consumption in such conditions can increase by 31%-34%. 

An increase in time spent on warming the engine to its optimum temperature, warming the seats, windows, mirrors and the air in the cabin, the reduction in performance of the battery - all of this has a negative effect on fuel efficiency.
Cold air increases  a vehicle’s wind resistance, especially at high speeds. Although this has a negligible effect on city driving, it can, all the same, noticeably increase fuel consumption for a run on the highway on a cold day.

Also, lowering of temperature increases the weight of the oil and other lubricants. And that means overcoming friction in the engine, the transmission and other components requires more work and more fuel.
Reduction in tire pressure in cold weather also doesn’t help with reducing consumption.

As a result, in the very same vehicle, fuel consumption in cold weather with difficult road conditions can increase all the way up to 50 percent compared with that in warm weather on dry roads.

However, hot weather too doesn’t help fuel efficiency, mainly due to use of the A / C. Also, it is worth bearing in mind that in extreme heat on overheated asphalt the possibility of tire damage at high speeds rises sharply.

Precipitation.

Snowy, wet roads, and black ice reduce tire grip on the road.The safe driving speed on a slippery road in poor visibility is significantly lower than normal. This increases fuel consumption even more, especially at speeds of lower than 50-60 km/hr. The need to use 4WD on roads with heavy snow coverage or when driving through thick mud after heavy rainfall leads to an extra increase in gasoline consumption.

Fog or thick cloud on mountain roads can reduce visibility to a minimum, which makes traveling extremely slow and dangerous.

Wind direction can also affect fuel consumption.
A strong headwind increases air resistance, a side wind complicates driving and brings with it a lower safe speed.

Currently, there already exist services which allow potential fuel consumption to be calculated for long journeys and which consider not only distances but also weather conditions.
OpenWeatherMap provides not only accurate forecasts and current weather reports for such calculations, but also historical weather data for any location.  Using this data, it is possible to more accurately establish whether fuel usage was appropriate to the length of the journey and road conditions.