SAN DIEGO — The remnants of Hurricane Boris created weather conditions that went down in San Diego County history.

According to the National Weather Service, heavy rains and thunderstorms swept the region in early June of 1990 as the tropical storm brought with it “a moist unstable air mass.”

Weather officials say Boris started as a “tropical wave” off the coast of Africa on May 20, 1990.

NWS describes a “tropical wave” as an elongated area of relatively low pressure (an inverted trough) or cyclonic curvature that moves east to west across the tropics.

This type of topical weather condition can lead to the formation of a tropical cyclone, which NWS says is also known as an “easterly wave.”

That’s exactly what happened in 1990 as Boris spent half a month drifting across the Atlantic and East Pacific oceans before ultimately developing into a hurricane in early June 1990, just off the west coast of Mexico.

To be considered a hurricane, NWS says a tropical cyclone has to have maximum sustained surface winds of 74 mph or greater.

Though San Diego generally isn’t considered an area where the effects of hurricanes are felt, weather officials say Boris “single-handedly produced the wettest June in San Diego since records began in 1850.”

On June 10, 1990, NWS records show 0.49 inches fell in the City of San Diego, marking the greatest one-day total for June in recorded history. Two-day rainfall totals during that same time reached 0.87 inches, according to the data.

In present day, there’s no remnants of hurricane weather brewing off the Southern California coast, however, some San Diego County areas woke to patches of drizzle as “June Gloom” persists.