temp keep raising

[blurrblurr]

recently change from internal filter to canister filter. Before the big change I can hit 26-27 degree. Now I always hit 27-28 degree. I thought temperature will go lower if external filter is use?
Using 3 fan to blow my 2ft tank. Last tempurature taken is 27.5 and is at night with no light on.
Is there any factor that cause temp to raise?

[vinz]

Maybe its just coincidence. Been fairly hot the last few days.

[Aeon]

The weather is terribly hot recently. no worries.
I get 27.5 on average and when it rained a few days ago, I got 26.