The U.S. average retail pump price for diesel in the U.S. crossed the $4 per gallon mark this week, while average retail pump prices for gasoline shot up over 15 cents per gallon over the last two weeks, due to colder-than-normal winter weather combined with civil unrest affecting Ukraine in Europe, Venezuela in South America, and the South Sudan in Africa.

In particular, cold winter temperatures across much of the nation are driving up energy demand. According to the Energy Information Administration (EIA), temperatures east of the Rocky Mountains have been significantly colder this winter (October 2013 thru January 2014 ) compared with the same period both last winter and the previous 10-year average, putting upward pressure on consumption and prices of fuels used for space heating.

The agency also noted in its most recent Short Term Energy Outlook report that U.S. average heating degree days were 12% higher than last winter (indicating colder weather) and 8% above the previous 10-year average. In terms of temperatures, EIA said data indicated the Northeast was 11% colder than last winter, the Midwest 17% colder, and the South 20% colder, while the West was 3% warmer.

EIA’s fuel price data for the week of February 24 recorded a 2.8 cent climb in diesel to $4.017 per gallon, though that price is 14.2 cents per gallon cheaper compared to the same week in 2013.

Diesel prices increased in all nine regions of the country, the agency reported, with diesel over $4 per gallon in: New England ($4.386), the Central Atlantic ($4.358), the East Coast ($4.148), the West Coast ($4.035), and the Midwest ($4.025).

Gasoline prices increased 6.4 cents this week to $3.444 per gallon, EIA said, which follows an 8.9 cent increase for the week of Feb. 17 – though this week’s price point of $3.444 per gallon is 34 cents per gallon cheaper compared to the same week in 2013, the agency’s data indicated.

The most expensive gasoline price is on the West Coast at $3.652 per gallon, while the Gulf Coast is home to the cheapest price at $3.209 per gallon. The biggest one-week spikes in gasoline prices occurred in the Rocky Mountains (8.3 cents to $3.322 per gallon) followed by the Midwest (8.2 cents to $3.439) and the west Coast (8 cents to $3.652).