PORTLAND, Ore. (KOIN) — Portlanders are days away from making it through another Pacific Northwest winter. As of Monday, we are officially one week away from the first day of spring. For Portland, this generally means milder temperatures, on-and-off rain and an explosion of seasonal flowers.

Portland’s average monthly temperature and rainfall. (NOAA)

March 20 marks the spring equinox, the first day of astronomical spring. On this day, the Earth’s Northern and Southern Hemispheres will receive nearly equal hours of daylight. Following the equinox, the Northern Hemisphere will see longer days and warmer temperatures as the Earth’s orbit and axis combine to point the top half of the Earth back toward the sun.

How earth’s axis creates seasons. (NOAA)

“Seasons are caused by the fact that the Earth is tilted on its axis by 23.5 degrees,” NOAA states. “The tilt’s orientation with respect to space does not change during the year; thus, the Northern Hemisphere is tilted toward the sun in June and away from the sun in December.”

As the region nears spring, we are also exactly 100 days from summer. This first day of summer, also known as the summer solstice, begins on June 21. On this day, the Northern Hemisphere will experience its maximum tilt toward the sun — the longest day of the year.