- Country: US
- State: IL
- Latitude: 41.856
- Longitude: -87.609
High Temperatures
On August 15 in NORTHERLY ISLAND the average high temperature is 79.6 °F (26.5 °C). The lowest recored high temperature was 73.2 °F (22.9 °C) in 2013 and the highest recored high temperature was 87.3 °F (30.7 °C) in 2015. The high temperature is usually* between 76.2 °F (24.6 °C) and 83.0 °F (28.3 °C). About a quarter of the time, the high temperature is less than 76.2 °F (24.6 °C), and another quarter of the time, the high temperature is greater than and 83.0 °F (28.3 °C). About 95% of the time, the high temperature has been between 69.8 °F (21.0 °C) and 89.5 °F (31.9 °C).
Low Temperatures
On August 15 in NORTHERLY ISLAND the average low temperature is 67.5 °F (19.7 °C). The lowest recored low temperature was 59.2 °F (15.1 °C) in 2014 and the lowest recored low temperature was 71.1 °F (21.7 °C) in 2020. The low temperature is usually* between 65.2 °F (18.5 °C) and 69.7 °F (20.9 °C). About a quarter of the time, the low temperature is less than 65.2 °F (18.5 °C), and another quarter of the time, the low temperature is greater than and 69.7 °F (20.9 °C). About 95% of the time, the low temperature has been between 61.0 °F (16.1 °C) and 73.9 °F (23.3 °C).
Frost
On August 15 in NORTHERLY ISLAND expect the temperatures to drop below freezing for a risk of frost about 0.0% of the time.
Data Source(s)
The data used to compute the average high/low temperatures for this location were taken from the following stations:
- NORTHERLY ISLAND — Integrated Surface Dataset (ISD) station ID: 998499 — from year 2012 to 2025