The spring-like weather pattern that dominated Albany through the months of January, February and March has abruptly shifted to a colder one. Currently, temperatures are 6.5 degrees below average through Tuesday.

This week’s chilly conditions are due to a southward plunging jet stream, which will ensure that Western areas see below-normal temperatures through the first part of this week. Seattle, for example, is expected to hit just 48 F on Monday and Tuesday when highs are typically closer to 60 F at this time of year.

The same thing is expected to happen in the Northern Plains as well, where low pressure will keep temperatures below normal. The good news is that the polar vortex will shift later this week, and warmer air will push into the Northeast and Midwest. That will bring temperatures closer to normal for the remainder of the month.

While it’s too early to tell how much longer these below-average temperatures will last, Environment Canada warns that the weather could remain cool and wet. If the arctic ridge that’s sitting over Manitoba persists, the temperature will continue to dip below normal.

If you’re traveling in the area this week, dress in layers. Start with a moisture-wicking base layer that will help to draw sweat away from your skin, then add a layer of insulating material and finish with a waterproof or windproof outer layer. This will ensure you’re warm enough while still remaining comfortable if the temps drop and the wind picks up.