- Country: US
- State: IL
- Latitude: 41.856
- Longitude: -87.609
High Temperatures
On August 20 in NORTHERLY ISLAND the average high temperature is 80.2 °F (26.8 °C). The lowest recored high temperature was 70.3 °F (21.3 °C) in 2024 and the highest recored high temperature was 86.4 °F (30.2 °C) in 2013. The high temperature is usually* between 76.8 °F (24.9 °C) and 83.7 °F (28.7 °C). About a quarter of the time, the high temperature is less than 76.8 °F (24.9 °C), and another quarter of the time, the high temperature is greater than and 83.7 °F (28.7 °C). About 95% of the time, the high temperature has been between 70.1 °F (21.2 °C) and 90.3 °F (32.4 °C).
Low Temperatures
On August 20 in NORTHERLY ISLAND the average low temperature is 67.6 °F (19.8 °C). The lowest recored low temperature was 61.0 °F (16.1 °C) in 2015 and the lowest recored low temperature was 73.0 °F (22.8 °C) in 2021. The low temperature is usually* between 65.1 °F (18.4 °C) and 70.0 °F (21.1 °C). About a quarter of the time, the low temperature is less than 65.1 °F (18.4 °C), and another quarter of the time, the low temperature is greater than and 70.0 °F (21.1 °C). About 95% of the time, the low temperature has been between 60.4 °F (15.8 °C) and 74.7 °F (23.7 °C).
Frost
On August 20 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