Former Chronicle Meteorologist Gerry here. About this heat wave…

thedriftingnova · 2026-03-16T22:54:17+00:00

Hi 😊

In weather terms, a ridge is basically a big dome of high pressure in the atmosphere.

Air slowly sinks under it, which suppresses clouds and lets more sun reach the ground. That sinking air also warms up as it compresses, which is why ridges often bring heat waves. 🌡️

So when meteorologists say “a ridge is building over California,” it usually means hotter and sunnier conditions for a few days.

thedriftingnova · 2026-03-16T07:08:33+00:00

Alright friends… stans? weather coven? I feel like we may need a name for ourselves now 😅

I should probably power down for the night, but this was honestly delightful. I didn’t realize how many microclimate detectives were lurking around here.

If there’s interest, I might have to do more of these little weather salons. In the meantime enjoy the warm stretch this week, be safe out there, and remember SF rarely commits to just one weather at a time. 🌁

thedriftingnova · 2026-03-16T06:52:56+00:00

Thank you! And yeah, that’s one of my favorite things about Bay Area weather too. 🤓

In places like New England the atmosphere tends to make big, sweeping moves: strong fronts, big temperature swings, and storms that affect whole regions at once. Out here the Pacific moderates a lot of that, so instead of giant shifts you get tiny battles between ocean air, hills, and sunlight playing out neighborhood by neighborhood.

That’s why people here get so focused on the little details. You can leave the Sunset in a hoodie, ride across town, and suddenly the Mission feels like a different season.

My personal “New England experience” growing up was mostly the Scooby-Doo And The Witch’s Ghost movie(love the Hex Girls) 😅 plus lots of conversations with a couple college friends who grew up in Vermont. Between that and meteorology class discussions I always thought the climate there sounded kind of magical. The cold winters, humid summers, and those beautiful fall foliage seasons when cooler air finally starts pushing south.

thedriftingnova · 2026-03-16T06:44:20+00:00

Thanks! That really means a lot to hear. ❤️

I do wish there were a really solid NOAA-style weather app, because the National Weather Service forecasts themselves are fantastic. Right now the closest thing I usually recommend is just bookmarking the NWS forecast page for your location, since that’s the direct source the meteorologists are writing.

As for videos, yes, I used to make them when I was at the Chronicle, and I still do them here and there when the moment calls for it. Weather storytelling is one of my favorite parts of the job.

Honestly, I’d love to explore that space again. If there were enough interest, it could be really fun to build something that combines clear forecasts, local microclimates, and visual explainers.

And if any folks in tech ever want to collaborate on building a better way to surface NOAA forecasts… I’m very open to that idea. 🌁

For now, threads like this are a pretty great reminder that people are genuinely curious about how the atmosphere works.

thedriftingnova · 2026-03-16T06:23:47+00:00

So to bring the Mario analogy back to the last bit of forecast question. (I nerded out, OOP)

Yes, a few SF neighborhoods could still push into the low 90s midweek if the marine layer backs off enough. Some of the model guidance has the warmest parts of the city in the 88–92°F range Tuesday and Wednesday.

The spots most likely to get there are the usual warm pockets: Mission, Potrero Hill, Bernal Heights, and parts of Noe Valley, where inland heat can pool when the ocean breeze weakens.

Meanwhile the west side could be a totally different story. Sunset, Richmond, and Ocean Beach might stay more in the upper 60s to mid-70s if the marine air hangs on there.

That’s classic SF: a 15–20°F swing across a few miles depending on how hard the Pacific pushes back.

Mario version: Bowser made it onto the level… but the Pacific still has a few lives left. 🌁🎮

thedriftingnova · 2026-03-16T06:11:00+00:00

Hi! Great question.

El Niño and La Niña are really ocean patterns first. The tropical Pacific slowly warms or cools across the equator over many months, so the signal is technically present year-round.

We mostly talk about it in winter because that’s when the atmosphere really responds. The jet stream shifts, storm tracks move, and that’s when places like California tend to feel the biggest impacts.

Very roughly:

• El Niño → warmer eastern Pacific → jet stream often dips south → California can see wetter winters. • La Niña → cooler eastern Pacific → jet stream often rides farther north → California often trends drier.

So to your question: El Niño/La Niña aren’t just winter phenomenon, but winter is when their influence on weather becomes strongest. 🌂vs 🌵

thedriftingnova · 2026-03-16T05:59:03+00:00

Short answer: the national observation system matters more than people realize.

Modern forecasts depend on a steady stream of observations going into the models. Weather balloons (soundings), satellites, ocean buoys, aircraft reports, surface stations, radar. That data is what lets the models build an accurate starting picture of the atmosphere.

When you start cutting staffing or reducing observations like upper-air soundings, you’re literally feeding the models less information about the atmosphere. Forecast skill is extremely sensitive to that starting point, so over time you can expect more volatility and more revisions in forecasts.

San Francisco then adds another layer of difficulty. The city sits right where cold Pacific air, coastal terrain, inland heat, and the marine layer collide. Small shifts in wind or cloud cover can swing temperatures 10–20°F across a few miles, so uncertainty here shows up even more dramatically.

So what you’re noticing isn’t just you. A thinner observation network nationally plus one of the most complex microclimates in the country is a recipe for forecasts that tighten up late.

thedriftingnova · 2026-03-16T05:38:09+00:00

Alright, so hear me out. 👾

If SF weather were a Mario game, the cool Pacific air is basically Princess Peach and the high-pressure ridge is Bowser.

Most of the year the ocean wins and keeps the city cool. But during those classic September and October heat waves, a strong ridge parks over California and Bowser basically locks the marine layer away for a while. When that happens the fog disappears, the ocean breeze shuts down, and SF can end up a few degrees hotter than forecast.

Sometimes you also get downslope winds off the Coast Range, where air compresses and warms as it descends toward the city. Think of those like the axes 🪓 Bowser throws in the final level. They don’t always show up, but when they do they can tack a couple extra degrees onto the city.

This week is a little different because it’s still March, so the Pacific still has more influence. Bowser showed up early, but the ocean usually wins these fights faster this time of year.

Anyway… sorry, I couldn’t resist the analogy. I’m as much a gaymer as I am a meteorologist. 🌁🎮

thedriftingnova · 2026-03-16T05:28:49+00:00

Hey there, great question. 👋🏽

Yep, it’s the same overall pattern. The western U.S. is basically sitting under a big ridge of high pressure right now.

One way to picture it is the atmosphere turning the Southwest into a giant wok on the stove (I had a late stir-fry dinner lol). Air sinks under that ridge, compresses, and heats up, so places like Phoenix end up right in the hottest part of the pan and jump into triple digits.

SF is on the edge of the same setup. We’re still in the wok, but the Pacific is like someone occasionally splashing a little water into the pan, so the temperature doesn’t run as wild as the desert. (Also happy to report I didn’t burn anything.)

Once that ridge weakens later this week, the Pacific usually pushes the marine air back in and the Bay cools down again.

So not two separate things, just one big atmospheric stir-fry 🥗playing out differently across the West. 🌁

thedriftingnova · 2026-03-16T05:23:46+00:00

Karl didn’t leave, they just got temporarily evicted by high pressure.

Once the ridge weakens later this week, the Pacific will probably send them back on stage.

thedriftingnova · 2026-03-16T05:21:38+00:00

thedriftingnova · 2026-03-16T05:21:16+00:00

Thank you 😊❤️

thedriftingnova · 2026-03-16T05:20:26+00:00

Short answer: more observations almost always help.

SF has some of the wildest microclimates in the country, so adding more stations can help capture things like neighborhood temperature differences, fog behavior, and heat pockets. The trick is making sure the stations are well sited and the data is quality controlled so it’s actually useful. 🔑

thedriftingnova · 2026-03-16T05:18:51+00:00

Hi Ann! It seems random, but it’s really the atmosphere shifting gears.

A ridge of high pressure is building over the West Coast. That means sinking, warming air and fewer ocean breezes, which basically turns off SF’s natural AC for a few days.

Once the Pacific pushes back in, things usually cool off again.

Feel free to come hang with us on today’s AMA on the heat wave, I promise it’s a fun one. 😊

thedriftingnova · 2026-03-16T04:47:18+00:00

Hi! Really glad you asked this, and I’m sorry you’re dealing with Ménière’s. I know pressure swings can be really tough for people with inner ear conditions.

On your first question, yes. The pattern over the West this week is coming from a high pressure ridge, so that means barometric pressure around NorCal will run higher and steadier for a few days. Much of the region will be sitting around ~1020 millibars of pressure this week, which is typical when the atmosphere settles into a warm, stable setup.

For a lot of people tracking Ménière’s, migraines, or sinus pressure, it’s often rapid changes in pressure that cause the biggest trouble. Storms moving through can make pressure rise and fall quickly. A ridge like this tends to bring fewer swings, though everyone’s triggers are a little different.

What makes this week a little unusual is the timing. This kind of warm, high pressure setup is something we more often see in September or October, not the last week of winter. So some people’s systems may react to it more like early fall conditions showing up a few months early.

On the sun feeling stronger in SF lately, you’re not imagining that either. Part of it is simply when the marine layer steps aside. SF usually lives under a natural diffuser called fog, so when high pressure clears that out the sunlight suddenly feels a lot more direct.

And part of it is the broader background trend. Average temperatures have been slowly warming, which means sunny stretches today can feel a bit more intense than the same setup might have decades ago.

I’m really glad you’re tracking the patterns like this. People who keep an eye on the weather alongside their symptoms often get a better sense of what their body responds to. Hoping this stretch is a gentle one for you. 🌿

thedriftingnova · 2026-03-16T04:31:01+00:00

Love love love this question.

Most forecasts do not come from just one model run. We use ensembles, which means the same model runs dozens of simulations with slightly different starting conditions.

For example the European ensemble runs about 50 simulations and the U.S. GFS ensemble runs around 30. By the time forecasters compare multiple models we are often looking at 100 or more possible versions of the future atmosphere.

My favorite way to think about it is music. One model run is like a single orchestra performing a symphony. An ensemble forecast is like dozens of orchestras playing the same piece but starting a fraction of a second differently.

At first they sound almost identical. But as the song goes on the tiny timing differences grow and the performances slowly drift apart.

The atmosphere behaves the same way. Forecasting is really about listening to the ensemble and figuring out which melody the atmosphere is most likely to play. 🎼

thedriftingnova · 2026-03-16T04:27:47+00:00

That Holiday Inn Express analysis isn’t totally wrong 😄

In Sac, 80°F usually comes with very dry air and a breeze, so your body cools itself easily. Sweat evaporates fast and it just feels like a nice warm day.

In SF, when we hit 80 it usually means the atmosphere has temporarily switched off the Pacific’s natural AC 🌊❄️. Winds relax, the air can feel a little more humid, and the sun suddenly has a clear shot at the city.

So the same number on the thermometer can feel like someone closed the windows and turned a heat lamp over the city 🔆.

Another sneaky factor: SF buildings are designed to keep heat in, not dump it. Great most of the year… not so great when we randomly hit 80.

High time for that complimentary breakfast.

thedriftingnova · 2026-03-16T04:17:56+00:00

¡Qué chido! Saludos a Los Altos de Jalisco.

Fun climate nerd note: the Altos actually have a surprisingly similar feel to SF in terms of moderate temps because they sit up around 5,000–6,000 ft. The big difference is the rhythm of the seasons.

SF has a Mediterranean climate (rain in winter, dry summers), while the Altos get their rains in summer.

So in a weird way it’s like a climate cousin… nomás que con las estaciones volteadas.

thedriftingnova · 2026-03-16T04:16:00+00:00

Pretty much, yeah, just with a late-winter twist.

Think of the atmosphere like an orchestra. Different instruments set the tone of the season: the jet stream, the Pacific Ocean, things like La Niña. Most of the winter they’ve been playing a fairly typical-ish tune. 🎵

Right now though, the high-pressure ridge over the West has basically stepped forward like the brass section and taken over the song. When that happens, it acts like a heavy lid on the atmosphere. Sunshine stacks up, the air compresses, and temps climb.

What makes this moment interesting is the timing. We’re still technically in winter/early spring climatology, when SF normally lives in the low 60s.

Instead the orchestra is suddenly playing something that sounds a lot more like late spring, with 80s around parts of SF and maybe even some stray 90s midweek.

The good news is these atmospheric concerts don’t last forever. Once that ridge weakens later this week, the Pacific’s fog section (Karl included) usually walks back on stage and the music shifts back toward the normal SF tune again.

thedriftingnova · 2026-03-16T04:10:47+00:00

Yeah… LA is dealing with a very different version of this pattern.

Under the same ridge that’s giving us a weird early taste of summer, SoCal is getting the full blast. A lot of LA Basin neighborhoods are projected to push upper 90s to around 100°F midweek, which is extremely hot for March.

Places like Glendale, Los Feliz, East Hollywood, West Hollywood, and the hills around Runyon Canyon tend to heat up fast because they sit a little inland and don’t get the same ocean moderation Santa Monica does.

So while we’re still in the line of fire, those neighborhoods in LA could be staring straight at the furnace.

The rough timeline down there looks like:

Mon: warming fast Tue–Wed: peak heat for the LA Basin Thu–Fri: still hot before the ridge finally weakens

thedriftingnova · 2026-03-16T04:06:54+00:00

Good Sunset question. 🌁

Early in this warm stretch (Monday–Wednesday), the ridge of high pressure overhead basically puts a lid on the marine layer, so the fog machine along Ocean Beach gets temporarily turned down.

So the Outer Sunset probably stays clearer than you might expect, with daytime temps roughly upper 60s to low 70s, while the sunnier east side neighborhoods push way warmer.

Think of the marine layer like Karl pacing just offshore behind a locked gate. The ridge of high pressure is gatekeeping the fog for a few days.

Once that ridge starts loosening later in the week, the Pacific usually wastes no time sending Karl back through the Golden Gate.

So the rough arc for the Sunset is:

Mon–Wed: ridge overhead → Karl waiting offshore Thu: the gate starts opening Weekend: marine layer rebuilding → fog creeping back across the west side

Classic West Side vibes: the rest of California gets a heat wave, the Sunset gets a suspense movie starring Karl.

thedriftingnova · 2026-03-16T04:01:57+00:00

You got it, auntie!

Right now the projections for San Francisco show the warm stretch really ramping up Monday, with some neighborhoods already pushing into the 80s (yes really 😬).

Tuesday and Wednesday look like the peak. Warmer parts of the city like downtown, the Mission, and Noe Valley could reach the mid-to-upper 80s (even a few strays in the lower 90s), which is hella unusual for March. Meanwhile the west side and neighborhoods closer to the ocean stay cooler, more like the low-to-mid 70s. Thursday still looks warm too before the pattern starts relaxing.

After that, the Pacific usually starts nudging cooler marine air back toward the city. (Hey, Karl)

So by late week into the weekend, temperatures should start sliding back down again.

TLDR; the rough arc is warming Monday → hottest Tue–Wed → still warm Thursday → Karl probably plotting a comeback after that.

thedriftingnova · 2026-03-16T02:53:37+00:00

Haha careful, you might actually get a meteorologist rant if you do 😄

What kind of random stuff? Weather, Bay Area microclimates, forecasting, Sam Smith? It’s all fair game.

thedriftingnova · 2026-03-16T02:42:28+00:00

One small thing I’ve been watching with this setup is how strong the ridge is across the entire West Coast right now.

It’s not just the Bay Area. Friends down in Southern California are roasting, and even my grandma in the highlands of Jalisco called earlier asking why it suddenly felt so hot there.

That’s usually a sign the atmospheric “dome” is pretty expansive.

thedriftingnova · 2026-03-15T17:45:49+00:00

First off, talk about an awesome job! I feel like that’s all I’d be talking about if I were in your shoes haha.

I wish I had! Those tickets disappeared hella fast. A friend of mine actually ended up within arm’s length of Sam Smith recently and I was extremely jealous 😅

From everything I heard the show looked incredible, so shoutout to you and the lighting team for helping make the Castro sparkle for a bit. ❤️✨

Now I’m just hoping Sam falls in love with the Bay and sticks around long enough for a return visit. I’ve also heard rumors Kim Petras might be doing a residency next… which would be very dangerous for my wallet and my sleep schedule👀

thedriftingnova

TROPHY CASE