I'm fermenting a porter, and pitched the yeast at about 75°F (24°C) on Sunday night (4 days ago). Lively fermentation started the next day, and though the wort had cooled to about 68°F (20°C) the first night, the fermentation brought it up to 72-74°F (22-23°C). There was 2 solid days of really active fermentation at this temperature. However, there's been a couple really cold nights, and now the CO2 bubbling out has slowed dramatically. The temperature got down to 65 yesterday, so I put a space heater near it, and it's now up to 76°F (24.5°C) - but the fermentation still seems really slow.
I'm wondering how the swing in temperature is going to affect it - any thoughts? Also, I'm going to be adding coffee and vanilla into secondary fermentation (in about another 4-5 days), how important is the controlling the temperature while in secondary?
Thanks for the help!