- Country: US
- State: IL
- Latitude: 41.856
- Longitude: -87.609
High Temperatures
On April 18 in NORTHERLY ISLAND the average high temperature is 59.6 °F (15.3 °C). The lowest recored high temperature was 39.0 °F (3.9 °C) in 2018 and the highest recored high temperature was 75.4 °F (24.1 °C) in 2025. The high temperature is usually* between 51.6 °F (10.9 °C) and 67.6 °F (19.8 °C). About a quarter of the time, the high temperature is less than 51.6 °F (10.9 °C), and another quarter of the time, the high temperature is greater than and 67.6 °F (19.8 °C). About 95% of the time, the high temperature has been between 36.4 °F (2.4 °C) and 82.9 °F (28.3 °C).
Low Temperatures
On April 18 in NORTHERLY ISLAND the average low temperature is 39.4 °F (4.1 °C). The lowest recored low temperature was 30.0 °F (-1.1 °C) in 2018 and the lowest recored low temperature was 49.5 °F (9.7 °C) in 2024. The low temperature is usually* between 35.6 °F (2.0 °C) and 43.1 °F (6.2 °C). About a quarter of the time, the low temperature is less than 35.6 °F (2.0 °C), and another quarter of the time, the low temperature is greater than and 43.1 °F (6.2 °C). About 95% of the time, the low temperature has been between 28.4 °F (-2.0 °C) and 50.3 °F (10.2 °C).
Frost
On April 18 in NORTHERLY ISLAND expect the temperatures to drop below freezing for a risk of frost about 9.4% 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 2013 to 2025