The last time we had snow on the ground in Edmonton at Halloween?  
2006.

The last time we stayed below zero on Halloween?
2006.

So...it's been a handful of years since the kids have had to deal with this type of weather.
To add to the "chill" this evening, wind will pick up.  So...it's going to feel like -10'ish late this afternoon & early this evening.

There's also a chance of wet snow late this afternoon into this evening.
A blast of milder air is pressing in from the SSW.  Ahead of that warmer air, we'll get some snow tonight.
That'll turn to a rain/snow mix Thursday morning in the Edmonton area & elsewhere in Central Alberta.
It looks like it'll stay snow for areas just north of Edmonton.  So, there are spots N & NE of the city that could pick up 5-10cm of snow tonight & Thursday.
Edmonton looks like it could see 2 or 3cm of snow.
The bigger concern will be the risk of freezing rain Thursday morning.

As for THIS morning...the concern has been the COLD!  -27 in Grande Prairie this morning & near -20 in parts of Central Alta.  
Not record-setting cold.  But easily the coldest temperatures of the season, so far.
By tomorrow, that cold air will slide east into Saskatchewan & milder air will drift into the province.

Edmonton Forecast looks like this:

Today - Cloudy. 60% chance of late-PM flurries.
Wind becoming SE 15-20km/h this afternoon.
High:  -5

Tonight - Cloudy with periods of wet snow.
Low:  -7

Thu - Rain/snow mix in the morning.  Cloudy, 40% chance of flurries in the afternoon.
High:  -2

Fri - Mix of sun & cloud.
High:  -2

Sat - Mix of sun & cloud.
High:  2

Sun - Mostly cloudy w/ a risk of late-day showers or flurries.
High:  4

Mon - Cloudy w/ sunny breaks.
High:  5