The sourdough temperature chart: what 65, 70, 75 and 80F do to your starter

These numbers describe roughly how long a healthy, established starter takes to peak (to rise to its maximum and just begin to dome or flatten) after a standard 1:1:1 feed. Treat them as a starting map, not gospel: your flour, your starter's strength and your hydration all nudge the exact timing. The point isn't the precise hour; it's the relationship. Once you internalise that warmer equals faster, you stop trusting recipe clocks blindly and start reading your own jar.

When the kitchen drops below ~21C, you have two honest options and they're both fine. Option one: give the starter a warmer home (the oven-light box, top of the fridge, a heat mat) so it keeps its summer schedule. Option two: change nothing about warmth and simply expect a longer peak, feeding once a day instead of twice and planning bakes around a 10-hour rise. The mistake is to do neither, keep the summer timing, see a flat jar at hour four, and conclude the starter failed.

Heat is the opposite problem and it sneaks up on people too. Above ~27C a starter races, peaks before you're ready, then collapses into a sour, hooch-topped slump if you don't catch it. In a hot kitchen, feed more often or with a stronger ratio (1:5:5 buys you more time before peak), use cooler feed water, and move the jar to the coolest spot you have. If a heatwave makes daily attention impossible, the fridge is your friend: chill it and feed weekly until the weather breaks.

A printed chart is a great starting point, but your real chart is the one your own kitchen writes. If you note the room temperature and the time-to-peak each feed, within two weeks you have a personal curve far more accurate than any generic table, because it bakes in your flour, your jar and your home. Sourdough Tracker is built to keep exactly this thread, and its feed reminders shift with your starter's actual pace instead of a fixed alarm, so the seasonal slowdown never sneaks up on you. Pair this with reading your rise percentage and you can predict your peak window to the hour.