Pack or skip
Insect repellent for London in September
Verdict
Pack it
Warm (66°F) plus 9 rainy days = mosquito conditions.
Why
London in September averages highs of 66°F, lows of 52°F, 9 rainy days.
That climate means insect repellent earns its space in the bag. Warm (66°F) plus 9 rainy days = mosquito conditions.