The exact same distance- half a day of walking- is used shortly prior to this, and they're running that distance to confront very distant trespassers within the story, so this seems to be used in a literal context.
The average walking rate of a human is 5.0 kilometers/hour, which I will halve (2.5 km/hr) in Kled's case, as he is a small yordle with short, stubby legs.
As for timeframe? Well, it's described as occuring "before he can get his hat tied down", so unfortunately I'll have to run some assumed timeframes, based on how long it would logically take one to get their hat tied down.
4 seconds (Low-end: casually pick up, make sure it's quite tight, fit it well just because)
3 seconds (Mid-end: a bit brisker, but still secure)
2 seconds (High-end: if you're in quite a hurry)
As for "half a day's walking", remember that a "day of walking" isn't usually an actual day. Often, it refers instead to the ~12 hours or so that the sun is illuminating the sky to some degree, and that someone's not stopped to eat/take a breather. So, half of that = 6 hours.
2.5 km -> 2500 m, x 6 = 15000 m
15000 m / 4 seconds = 3750 m/s, or Mach 11.02.
15000 m / 3 seconds = 5000 m/s, or Mach 14.69.
15000 m / 2 seconds = 7500 m/s, or Mach 22.04.
Solid Hypersonic+, and it ought to scale to the movement speed of basically everyone else given Kled+Skaarl ain't exactly speedsters of the verse. I'll go with mid-end unless there's reason not to...?
Final Tally[]
Skaarl Ran: 5000 m/s