It’s clichéd to say “it’s not the heat it’s the humidity” but there’s a reason why that phrase is so overused around here. Indeed, the humidity is going to be oppressive for the foreseeable future.
How long can this last?
Since it didn’t reach 90 degrees on Wednesday in Boston, it’s unlikely that we will achieve a record heat wave. The longest heat wave in the city is 9 days and since records are measured at Logan Airport, a feeble sea breeze for a day can break a string of 90-degree weather.
The last time we had two heat waves that lasted five or more days in the same season was 2013. In July of that year, we had a a five-day heat wave, and then another that lasted seven days.
Over more inland areas, the 90-degree weather started on Tuesday, making Friday the fourth day of this kind of heat. There’s a chance this goes until Tuesday or Wednesday of next week, which means an eight- or nine-day heat wave for those inland.
The unbroken string of heat and humidity can take its toll on all of us and if you notice your energy is a bit lower and your mood isn’t so great, this kind of prolonged, uncomfortable weather can have that effect.
What about showers?
Your smartphone probably shows some showers nearly every day into next week. In reality most of the time is actually going to be dry, but hopefully by the time we get to next Wednesday, all of us will have experienced at least one downpour. The drought is so firmly in place that it will take days of rain, not a few showers, to make a difference.
The risk of showers is highest inland today and tomorrow. I think the risk for Sunday is actually a little bit lower before increasing again in the Tuesday-Wednesday timeframe. I would not cancel any plans but I would be aware that you may have to duck inside as any showers would contain heavy tropical downpours.
When does it end?
I feel fairly confident that by the time we get to next weekend, we’ll see a significant break in the heat and humidity. But exactly which day this occurs is still unclear.
The forecast guidance we use is having trouble resolving the end of this heat wave, which is not unexpected. When the atmosphere is stuck in a pattern like this, predicting the end can be difficult.
We can probably expect to see a transition to lower humidity around Aug. 10 or 11, but that means nearly a week before we get some really refreshing air.
If it’s earlier than that, we’ll be pleasantly surprised. Stay hydrated!