San Diego County drivers are paying $5.914 per gallon for regular unleaded as of Friday, March 27 — up more than a dollar from a month ago — as the Iran conflict enters its 28th day with no end in sight.

The immediate driver: Iran formally prohibited all shipping through the Strait of Hormuz Friday, threatening "harsh measures" against any vessel attempting to transit the critical waterway, according to BBC News. The Strait handles roughly 21% of the world's petroleum supply. With it effectively shut, markets are pricing in the possibility of prolonged disruption.

President Trump extended his five-day cease-fire on Iranian energy infrastructure Thursday night, pushing the pause deadline to April 6. Trump said Iran had requested the extension, but Iranian state officials denied any formal discussions with Washington had taken place. Iran also rejected the White House's 15-point peace plan, submitted via Pakistan, and instead issued its own five-demand counter-proposal.

Oil markets reacted skeptically. Brent crude climbed to $104.33 per barrel Friday while West Texas Intermediate rose to $97.04. The Pentagon is weighing deploying up to 10,000 additional ground troops to the Middle East, according to a Wall Street Journal report. Analysts at Macquarie warned that if the Strait remains closed through the end of June, prices could reach $200 per barrel — a scenario that would push San Diego pump prices well above $7 per gallon.

For Santee and East County commuters already stretching household budgets, the April 6 deadline is one to watch. If diplomatic progress stalls and the Strait stays closed, expect prices at local stations to continue climbing through the spring.