Maybe coincidence but 2016 seems like there's been less opportunity. I would guess Yahoo and Twitter (and others) are losing engineers which are hitting the market.
Is this a good time to look or better to keep a "safe" job?
If you are not learning anything in your current job then you are wasting time. Figure out something to learn, it will make your job more interesting (and more fun) and it will help you in the future with knowledge.
Engineering jobs are always plentiful and scarce at the same time, they are plentiful for the people who know and/or have experience in the new hotness, they are scarce for people who have skills for things that people are not using in abundance.
No such animal as a "safe job", even the postal service is eliminating people.
As you evaluate a prospective employer-- consider their business model and markets they serve. Are they expanding? Does the senior leadership have experience and stability?
Relative to Yahoo/Twitter engineers-- some of those guys are getting fat severance packages and plan to chill on the beach for the next 18 months. Don't worry about them. Move when the right opportunity lines up for you.
If you're not unhappy where you are--adequate salary, good living conditions--then take things slowly...
Land the next job before leaving your current one, and only if it represents a step up in responsibility and seems interesting, or otherwise improves your "life"...
Look at the headlines on the worldwide economic situation just now...yes, things are a bit uncertain...do your homework before making a jump...
And don't undervalue having a job when things are uncertain...just think about the alternative...
It could very well be affecting the tech market.
Overall, though, the American economy is continuing to improve. Greater world events are rattling the markets, and tech has taken a hit, but it doesn't seem out of the ordinary.
My question is SV-centric, but broader viewpoints would be useful as well.