Weekend forecast: Temps retreat a bit Saturday, hot on Sunday; less humid

Dew points creep up Sunday afternoon

I’ll have your weekend forecast details in a bit. First, here’s an important update on our current heat wave.

High temperatures will reach the upper 90s across much of Minnesota and parts of western Wisconsin this Thursday afternoon. A few spots could hit or exceed 100 degrees. The heat index will reach or exceed 100 degrees in many areas.

Here’s the National Weather Service definition of heat index and why it’s important:

The heat index, also known as the apparent temperature, is what the temperature feels like to the human body when relative humidity is combined with the air temperature.  This has important considerations for the human body's comfort.  When the body gets too hot, it begins to perspire or sweat to cool itself off.  If the perspiration is not able to evaporate, the body cannot regulate its temperature.  Evaporation is a cooling process.  When perspiration is evaporated off the body, it effectively reduces the body's temperature.  When the atmospheric moisture content (i.e. relative humidity) is high, the rate of evaporation from the body decreases.  In other words, the human body feels warmer in humid conditions.  The opposite is true when the relative humidity decreases because the rate of perspiration increases.  The body actually feels cooler in arid conditions. 

An excessive heat warning began at 11 a.m. Thursday in the Twin Cities metro area and continues to 8 p.m. this evening. A heat advisory (shaded orange) continues until 8 p.m. in much of Minnesota plus several counties in western Wisconsin:

Thursday heat advisories and excessive heat warnings
National Weather Service

Here are details of the excessive heat warning:

URGENT - WEATHER MESSAGE National Weather Service Twin Cities/Chanhassen MN 329 AM CDT Thu Jun 10 2021 MNZ060>063-068>070-102345- /O.CON.KMPX.EH.W.0001.210610T1600Z-210611T0100Z/ /O.CON.KMPX.HT.Y.0001.000000T0000Z-210610T1600Z/ Hennepin-Anoka-Ramsey-Washington-Carver-Scott-Dakota- Including the cities of Minneapolis, Blaine, St Paul, Stillwater, Chanhassen, Chaska, Victoria, Shakopee, and Hastings 329 AM CDT Thu Jun 10 2021 ...HEAT ADVISORY REMAINS IN EFFECT UNTIL 11 AM CDT THIS MORNING... ...EXCESSIVE HEAT WARNING REMAINS IN EFFECT FROM 11 AM THIS MORNING TO 8 PM CDT THIS EVENING... * WHAT...Dangerously hot conditions with heat index values up to 101 expected on Thursday afternoon and early evening. * WHERE...Hennepin, Anoka, Ramsey, Washington, Carver, Scott and Dakota Counties. * WHEN...For the Excessive Heat Warning, from 11 AM to 8 PM CDT Thursday. For the Heat Advisory, until 11 AM CDT Thursday. * IMPACTS...Extreme heat and humidity will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities. PRECAUTIONARY/PREPAREDNESS ACTIONS... Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances. Take extra precautions if you work or spend time outside. When possible reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose fitting clothing when possible. To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location. Heat stroke is an emergency! Call 9 1 1.

Before you keep reading ...

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Here’s a summary of heat safety tips from the National Weather Service:

Heat safety tips
National Weather Service

You can hear updated weather information for Minnesota and western Wisconsin on the Minnesota Public Radio network, and you can see updated weather info on the MPR News live weather blog.

Hot streak is at 8 days

Our Twin Cities temperature was 90 degrees at 11 a.m. Thursday, and we’re expected to top out in the upper 90s this afternoon. This is our eighth consecutive day with a high of 90 degrees or warmer in the Twin Cities:

Twin Cities heat wave
National Weather Service

We’ll probably top 90 again on Friday, extending our streak to nine days.

Weekend forecast

Saturday highs will retreat to the 80s in many areas, with some 70s in far northern Minnesota and a few 90s in the southwest:

Saturday forecast highs
National Weather Service

Saturday afternoon dew points will be in the comfortable 40s in many locations:

Saturday 1 p.m. forecast dew points
National Weather Service

Sunday high temperatures return to the 90s in most spots, with 80s in far northern Minnesota:

Sunday forecast highs
National Weather Service

It’ll feel a bit more humid by Sunday afternoon, as dew points creep into the 50s:

Sunday 1 p.m. forecast dew points
National Weather Service

At this point, it looks like Saturday and Sunday will be rain-free in most locations.

Programming note

You can hear my live weather updates on MPR News at 7:35 a.m., 9:35 a.m. and 4:39 p.m. each Saturday and Sunday.