2-4″ forecast for this weekend so be prepared for cold weather.  Snowshoes are not needed just yet.  Warm, water-repellent clothing is needed.
Some good advice from Matt:

could have anywhere from no snow at all to 3-5 feet of snow [in the next month]. It’s just very hard to say at this time. I have seen both (no snow
and lots of snow) types of weather at that time of year. Most likely,
their will be some snow though. We keep very up to date current weather
conditions as they change posted on our website.

The hike in is 2 miles all uphill with almost 1100 feet of elevation
gain. In the event of snow, the hike is a half mile longer and we do
recommend some sort of extra winter traction. Such as snowshoes,
yaktrax, or instep crampons. However, our trail crosses no avalanche
chutes, or glaciers. I would rate our winter trail as beginner to
intermediate and consider it very safe to hike/snowshoe.

Some advice from Rick:

Expect the worst . . . weather changes on a dime in the Cascades (especially at the elevation of the springs (3,520ft) and with the weather patterns funneling through Stevens Pass nearby.

Tell someone where you are going, when, and what time you are expected back.  Then make that phone call to let them know you are okay.

Have multiple ways of starting a fire in case that becomes necessary in a survival situation.  Please note that Scenic is within a fire-restricted area and that fires should only be resorted to in a survival situation.

Pack three days of something to eat (calorie-wise, dark chocolate is full of carbohydrates and slower burning fats to keep your core body temperature up.  Dehydration is not only a problem in hot weather . . . in cold weather we also dehydrate at a fast rate as we breathe our moisture out with every breath.  Colder air is also dry air as it can no longer hold the water vapor in the air (think rain and snow falling out of that air).  That dryer air is going to draw moisture away from your skin further adding to the problem of dehydration.  And then, of course, we are going to immerse ourselves in hot spring waters and sweat a lot more water out of our bodies.  Carry and drink plenty of water.  It is not a bad idea to carry a small electrolyte-replacement packet to deal with symptoms of moderate to severe dehydration.

Dress in layers so that you can remove or add clothing as the outside temperature changes.  The hike can be rigorous, causing you to sweat and dampening your clothing.  The outermost layer should be a water-repellent coat  Wet clothing can quickly lead to hypothermia.  Wear a wicking underlayer to pull moisture away from your skin.  Avoid cotton at all costs because when cotton gets damp or wet it saps body heat rapidly. The single most important item is a hat as we can lose up to 50% of our body heat through the head.  Don’t forget gloves.  Wear appropriate footwear . . . sneakers do not hack it in the cold, wet months of fall and winter.

Pack a large 33-45 gal plastic trash bag with you.  While you soak your pack, clothes, and boots can be stuffed inside and kept dry from the elements. Leaving, that same trash bag can be used to help remove litter from the site or, in a pinch, can be used as an impromptu poncho by poking three holes through the bottom and pulling it over your arms and head.

Get out of the hot spring pools in stages, drying the upper body and donning a top, then rising higher to dry the lower body and then finish dressing.

Carry a flashlight or headlamp.  The days are getting shorter and you do not want to be caught on the mountainside halfway back down and suddenly in darkness. 

Carry that cell phone and keep it’s battery warm.  It’s not a bad idea to keep a cell phone in a water-proof zip-lock baggie when you’re around so much water.   Cell phones often work on the trail and up at the springs.