Toshima's winter months, January and December, are marked by cold temperatures ranging from -7°C to 18°C and -7°C to 20°C respectively. As spring approaches in March and April, temperatures gradually warm up to averages of 12°C and 14°C respectively. Summer heats up significantly from May to August, with average highs reaching as high as 27°C during this period. Autumn brings a slight cool-down in September and October, but temperatures can still reach up to 30°C. The temperature range narrows again in November, returning to winter-like conditions before the cycle repeats itself.