WeatherWatcher: Weekly Weather, Summer of Thunder

• Forecast
• Heatwave and Thunderstorms
• Last week's data

Forecast: We are transitioning more and more into the fall weather patterns now. More seasonable weather will be moving in this week with showers off and on all week long. Some sun breaks will make it through as well. Expect high temperatures to average from the mid 60's to around 70. Lows will start to dip down into the low to mid 50's now.

Heatwave and Thunderstorms: We had a little one and a half day heat wave last week peaking on Wednesday with a high temperature of 89.7°F, which we can round and call it a high of 90°F.  Seatac official daily record was broken at 93°F, previous record was set in 2009 at 87°F. To be clear, this is just the record for the daily high on September 11th, other September days have been warm in the past as well. Locally we were at 85°F September 11, 2009. This was the second warmest day our entire summer, June 28, 2013 beat last Wednesday with a high temperature of 91.6°F.

Thunderstorms are hitting the area again Sunday evening. This is one of the most active summers for thunderstorms that we have had in at least 20 years. The latest batch of thunderstorms was caused by a trough of low pressure moving in from off the northern California coast. Once again we had more warm, moist air up from the southwest coast. If this type of weather pattern persists into the fall it could generate some significant wind storms for the region.

Last week's data:

High temperature: 89.7°F (Wednesday)

Low temperature: 55.6°F (Sunday)

No measurable rainfall last week.

Warmest day: 70.9°F (Wednesday)

Coldest day: 61.3°F (Friday)

Average temperature last week: 64.2°F (2.9 degrees warmer than normal.)

Station historic average: 61.3°F

Daily Average Temperature for September

Warmest and coldest days are based on average temperature of the entire day, starting at midnight. All other averages are based on the whole week, starting Saturday morning at midnight. All weather data unless otherwise noted is sourced from Carl's weather station located in the Echo Lake neighborhood of Shoreline, Washington. For up to the minute weather conditions and historic data, as well as links to weather information and resources, check out my page.

Follow me on Twitter: @SWeatherWatcher for any updates on weather events approaching our area.