October in Kallithéa, Greece, brings average daily highs of 25°C and overnight lows of 16°C in the 2016–2025 historical record. Light clothing is a useful starting point, with room in the plan to pause indoors. Decide how much walking to fit into each day using the local forecast, rather than treating the monthly average as a limit.
In the record, at least 1 mm of rain or snow falls on 3 of 31 days on average, a daily chance of 9%. Rain has been relatively infrequent in this record, which leaves more scope for an outdoor plan. Still keep an alternative for a wet day: a low monthly average cannot tell you when the rain will arrive.
The calculated day length, sunrise to sunset, averages about 11 hours. Sunshine averages 10 hours a day. Use the daylight window to plan the length of excursions, and check local sunrise and sunset times for the dates of your stay. Sunshine is a separate measure, and those hours need not arrive in one uninterrupted stretch.
Start with the places you most want to visit, then keep the order flexible enough to suit the weather. Check current opening hours and local transport before fixing long day trips. The climate record can help with pacing and packing, but it does not describe what is open during your stay.
November has an average daily high of 20°C, 5°C lower than October. Its historical rain-day chance is 22%, compared with 9% this month. If your dates are flexible, compare those trade-offs with the kind of days you want. Neither set of averages predicts the conditions of one particular holiday.