Vol in weekly SPX at the money options is 4.6 (Wed expiration calls) and under 6 for Fridays weekly expiration at the money options. Don't ever remember seeing it this low. Not sure it means anything other then very little movement is expected.
Low vol is kind of like a flattening yield curve: it precedes the shit hitting the fan, but isn't that useful because no one knows the time frame. It could be hours, days, weeks, months, or years before the next major downturn in SPX.