Don't be surprised to see a higher hydro bill this month — and no, it's not because of your Christmas lights and holiday cooking.

Effective Jan. 1, 2019, rates are rising $6.33 per month for typical residential users before tax — an increase of 5.4 per cent for customers who consume 750 kilowatt-hours per month, according to Toronto Hydro.

As of January 1, 2019, the Delivery Charge on your bill increased. The rates reflect changes in distribution and transmission charges, as approved by the Ontario Energy Board. (1) —@TorontoHydro A typical residential customer consuming 750 kilowatt-hours (kWh) will experience an average increase of $6.33 or 5.4% on the total monthly bill.<br>Learn more about the rate change: <a href="https://t.co/scsuBhC04r">https://t.co/scsuBhC04r</a> (2) —@TorontoHydro

The increase reflects changes in distribution rates approved by the Ontario Energy Board (OEB), along with changes in transmission and generation costs, the utility says.

Here's how the costs break down, according to Toronto Hydro's website:

$1.43 — Grid investments

$1.96 — Ending a credit that gave customers credit for property sales

$1.98 — Generation costs collected for entities such as the Ontario Power Generation

$0.96 — Transmission system costs collected for Hydro One and other entities

Electricity commodity rates are generally updated by the Ontario's energy regulator, the OEB, twice a year.

The utility also says parts of consumer's bill are expected to drop in 2020, but it's not yet clear by how much.