July Weather in Mercer Island, United States

Last updated: June 24, 2025

In July, the average temperature in Mercer Island, United States hovers around 19°C (67°F). Expect a minimum of 11°C (52°F) and a maximum reaching 32°C (91°F). With an average precipitation of 18 mm (0.7 in) spread over 5 days, the air tends to feel humid with an average humidity of 79%.

July Temperature in Mercer Island

In July in Mercer Island, the average temperature is 19°C (67°F). Maximum temperatures can reach 32°C (91°F), while minimums can drop as low as 11°C (52°F). This makes it a great time for travelers to enjoy outdoor activities, as the weather is pleasantly warm with a comfortable range for exploration.

July Weather in Mercer Island: Daily Temperature Highs, Lows, and Averages

The chart illustrates July temperature patterns in Mercer Island, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Mercer Island, July typically has an average temperature of 19°C (67°F), with highs reaching up to 32°C (91°F) and lows dropping to around 11°C (52°F).

Data source: Temperature data for Mercer Island generated using information from the Copernicus Climate Change Service.

July Precipitation in Mercer Island

In Mercer Island in July, the precipitation amount is 18 mm (0.7 in) spread over a duration of 5 days.

July Precipitation Trends in Mercer Island

The chart displays monthly precipitation patterns in Mercer Island, with values for each month alongside July’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how July’s conditions compare to those of other months. In Mercer Island, July typically receives around 18 mm (0.7 inches) of precipitation spread over approximately 5 days.

Data source: Precipitation data for July generated using information from the Copernicus Climate Change Service.

Choose your preferred precipitation unit

Millimeters (mm) Inches (in)

July Humidity in Mercer Island

In Mercer Island in July, humidity is 79%. With an average temperature of 19°C (67°F), this humidity feels like a warm, enveloping blanket that makes traveling a bit more challenging, as the air is thick and can leave you feeling sluggish during outdoor adventures.

July Average Humidity in Mercer Island

This chart illustrates the average monthly humidity levels in Mercer Island, with July’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In July, average humidity in Mercer Island is approximately 79%, offering insight into how humid the weather typically is during this month.

Data source: Humidity data for July generated using information from the Copernicus Climate Change Service.

July UV Index in Mercer Island

In Mercer Island in July, the maximum UV index is 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check the Hourly UV Index in Mercer Island.

Maximum UV Index Levels in Mercer Island for July

The chart shows the monthly maximum UV Index (UVI) for Mercer Island in July, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In July, the maximum UV index in Mercer Island typically reaches 9, which falls under the very high exposure category.

Data source: Mercer Island July UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

Extreme (11+): Avoid the sun, stay in shade.
Very High (8-10): Limit sun exposure.
High (6-7): Use SPF 30+ and protective clothing.
Moderate (3-5): Midday shade recommended.
Low (0-2): No protection needed.

How July Weather in Mercer Island Compares to Other Months

Weather in Mercer Island varies notably across the year, with each month offering distinct climate conditions. This page compares July’s weather to other months in Mercer Island, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Mercer Island, showing how July’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	6°C (43°F)	175 mm (6.9 inches)	86%	low
February Weather	5°C (41°F)	177 mm (7.0 inches)	86%	moderate
March Weather	7°C (46°F)	126 mm (4.9 inches)	87%	moderate
April Weather	10°C (50°F)	117 mm (4.6 inches)	84%	high
May Weather	14°C (57°F)	68 mm (2.7 inches)	81%	very high
June Weather	17°C (62°F)	63 mm (2.5 inches)	82%	very high
July Weather	19°C (67°F)	18 mm (0.7 inches)	79%	very high
August Weather	19°C (67°F)	16 mm (0.6 inches)	63%	very high
September Weather	16°C (62°F)	100 mm (3.9 inches)	62%	high
October Weather	11°C (52°F)	155 mm (6.1 inches)	83%	moderate
November Weather	8°C (47°F)	181 mm (7.1 inches)	89%	low
December Weather	6°C (42°F)	196 mm (7.7 inches)	88%	low