Kingshuk Mondal / CC BY 4.0
Thornton, CO Weather on August 18
August 18th in Thornton, CO typically brings warm summer weather, with average highs around 88°F and lows near 56°F — a 32°F daily swing. Over 55 years of records, the warmest August 18th was in 2024 (80°F average), while the coldest was 2008 (62°F) — a 18°F range across recorded history. Rain or other precipitation has occurred on about 29% of August 18th dates historically, with the wettest August 18th recording 0.58" of rain. The last decade has been 3.7°F warmer on this date compared to 20-30 years ago.
What to Expect on August 18
Planning for August 18th in Thornton, CO? Stay hydrated and seek shade during peak afternoon hours.
August 18 Weather Records for Thornton
- •The all-time record high for August 18th in Thornton, CO is 101°F, set in 2024.
- •The coldest August 18th on record dropped to 49°F in 2015.
- •Temperatures have reached 90°F or higher on August 18th in 26 of the last 55 years.
Frequently Asked Questions
What was the warmest August 18 ever in Thornton?
The warmest August 18 in Thornton, CO reached 101°F in 2024. That is 13°F above the long-term average high of 88°F.
What was the coldest August 18 ever in Thornton?
The coldest August 18 in Thornton, CO dropped to 49°F in 2015. That is 7°F below the long-term average low of 56°F.
What is the average temperature on August 18 in Thornton?
On August 18, Thornton averages a high of 88°F and a low of 56°F based on 55 years of NOAA weather observations from NORTHGLENN.
How many years of weather data are available for August 18 in Thornton?
We have 55 years of weather records for August 18 in Thornton, CO, sourced from NOAA's Global Historical Climatology Network. Records include daily high and low temperatures, precipitation, and snowfall data going back to 2025.
August 18 Weather History in Thornton
| Year | High | Low | Precip | Snow |
|---|---|---|---|---|
| 2025 | 99°F | 58°F | 0" | -- |
| 2024 | 101°F | 60°F | 0" | -- |
| 2023 | 97°F | 62°F | 0" | -- |
| 2022 | 87°F | 55°F | 0" | -- |
| 2021 | 97°F | 59°F | 0" | -- |
| 2020 | 98°F | 61°F | 0" | -- |
| 2019 | 93°F | 57°F | 0.01" | -- |
| 2018 | 92°F | 57°F | 0" | -- |
| 2017 | 91°F | 54°F | 0" | -- |
| 2016 | 93°F | 54°F | 0" | -- |
| 2015 | 79°F | 49°F | 0.13" | -- |
| 2014 | 93°F | 57°F | 0" | -- |
| 2013 | 97°F | 57°F | 0" | -- |
| 2012 | 86°F | 53°F | 0" | -- |
| 2011 | 93°F | 56°F | 0" | -- |
| 2010 | 86°F | 58°F | 0" | -- |
| 2009 | 74°F | 51°F | 0.17" | -- |
| 2008 | 72°F | 52°F | 0" | -- |
| 2007 | 90°F | 57°F | 0.04" | -- |
| 2006 | 92°F | 60°F | 0" | -- |
| 2005 | 91°F | 61°F | 0" | -- |
| 2004 | 89°F | 58°F | 0" | -- |
| 2003 | 90°F | 60°F | 0" | -- |
| 2002 | 100°F | 55°F | 0" | -- |
| 2001 | 92°F | 51°F | 0" | -- |
| 2000 | 73°F | 56°F | 0.06" | -- |
| 1999 | 86°F | 53°F | 0" | -- |
| 1998 | 94°F | 62°F | 0" | -- |
| 1997 | 82°F | 60°F | 0.02" | -- |
| 1996 | 81°F | 52°F | 0" | -- |
| 1995 | 91°F | 57°F | 0.03" | -- |
| 1994 | 89°F | 60°F | 0" | -- |
| 1993 | 80°F | 60°F | 0.03" | -- |
| 1992 | 79°F | 50°F | 0" | -- |
| 1991 | 82°F | 54°F | 0" | -- |
| 1990 | 82°F | 53°F | 0" | -- |
| 1989 | 87°F | 60°F | 0" | -- |
| 1988 | 83°F | 55°F | 0" | -- |
| 1987 | 81°F | 50°F | 0" | -- |
| 1986 | 96°F | 59°F | 0" | -- |
| 1985 | 78°F | 51°F | 0" | -- |
| 1984 | 83°F | 61°F | 0.01" | -- |
| 1983 | 89°F | 60°F | 0.06" | -- |
| 1982 | 90°F | 60°F | 0.05" | -- |
| 1981 | 84°F | 52°F | 0" | -- |
| 1980 | 92°F | 52°F | 0" | -- |
| 1979 | 76°F | 54°F | 0.06" | -- |
| 1978 | 85°F | 51°F | 0.14" | -- |
| 1977 | 80°F | 60°F | 0.05" | -- |
| 1976 | 87°F | 54°F | 0.05" | -- |
| 1975 | 90°F | 53°F | 0" | -- |
| 1974 | 91°F | 51°F | 0" | -- |
| 1973 | 91°F | 61°F | 0" | -- |
| 1972 | 89°F | 56°F | 0" | -- |
| 1971 | 89°F | 63°F | 0.58" | -- |
Based on 55 years of data from NOAA station: NORTHGLENN
Monthly Climate Averages
Historical temperature and precipitation averages for Thornton, CO, based on 55+ years of weather data.
Temperatures in Fahrenheit. Precipitation and snowfall in inches.