Timing out next week's heat event in Northern California and why your weather app may mislead you

A milder weather pattern returned as of Thursday, keeping Northern California highs closer to average during the afternoons.

Temperatures will begin to warm as the weekend approaches, but the main focus for the next few days is on a large heat event as we begin July.

Here's what's changing

Starting Sunday, temperatures begin to warm with many in the Sacramento Valley reaching for the upper 90s and a few triple digits. This will be the beginning of what's expected to be a hot first week of July.

On Monday, a strong ridge of high pressure starts to build off the coast of California, expanding eastward and strengthening through the week.

As the ridge builds, heat increases as air sinks and compresses, leaving behind the potential for multiple days of triple-digit heat for the valley. The closer the ridge of high pressure is to California, the greater the chances of very hot temperatures region-wide.

As of Thursday, models are keeping the strong ridge in place through the 4th of July. This means could be holding on to temperatures ranging from 100-110 degrees through the majority of the workweek and holiday weekend.

If the forecast pans out, this would be considered a heat wave and the hottest temperatures of 2024 so far. An Excessive Heat Watch has been issued from Monday to Thursday.

Be careful trusting your weather app

Looking up the forecast is an easy thing to do with weather apps on your phone these days. But it's important to check other sources too, as the apps are often times wrong.

Many experienced this and a slight panic on Thursday, June 27 as their favorite weather app posted a high of 119 degrees in Sacramento next Saturday, July 6. But then a few hours later, the app refreshed and showed a high of 105 degrees.

The reason weather apps like the one on your Apple devices show temperatures that high is because they don't handle valley heat waves well.

Many apps use only model data with no meteorologist intervention and like our forecasts, the models can change. This is why it helps to have a real person double-check things.

Weather apps use several weather models, but the most common is The Global Forecast System, commonly known as GFS. This is a longer-range forecast model that's updated every six hours. It's popular because it can give data for forecasts 16 days in advance.

A high of 119 degrees would be an all-time record for Sacramento and is very unlikely. The hottest day ever recorded in Sacramento was 116 degrees on September 6th, 2022.

Next week is going to be hot, but highs above 110 degrees look unlikely at this point. Being over eight days out, it's important to continue to check the forecast to see how this heat event evolves. The closer we are in time, the better the accuracy of the forecast.

Looking ahead

It's important as we get closer to next week to keep checking in with local forecasts and trusted meteorologists. There's still uncertainty about the duration of the heat event.

Prolonged heat could lead to heat illnesses and could bring local impacts. Make sure to take the steps now to check your air conditioner works properly. Have a plan to keep yourself, your loved ones, and your pets cool as the heat arrives.

Try to avoid the peak heat times of the day from 2 p.m. to 6 p.m. Stay hydrated through the day and wear sunscreen.

Stay with the CBS Sacramento First Alert Weather team as we time out the heat on the way.