You’re driving down I-30, maybe heading toward Dallas or pulling off to see the downtown square, and you think you know what to expect. It’s Texas. It’s going to be hot, right? Well, yeah. But mt vernon tx weather is actually a bit of a trickster.
If you just look at the yearly averages, you'll see a pretty standard 75-degree high. That sounds lovely. It sounds like a permanent spring. Honestly, that number is a total lie. It’s a mathematical average of two extremes that rarely meet in the middle for long. One week you’re scraping ice off a windshield in 30-degree humidity that cuts through a parka, and by Tuesday, you’re sweating through a cotton shirt because the dew point decided to jump to 70.
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The Muck and the Muggy: Summer Reality
Summer in Mount Vernon officially kicks off around early June and doesn't really let go until late September. We aren't talking about the dry, "it's a dry heat" vibe of West Texas or Arizona. This is East Texas. It’s wet.
The average high in August sits around $93^{\circ}F$ or $94^{\circ}F$. But that’s just the air temperature. When you factor in the moisture rolling off the Gulf and settling into the Piney Woods, the "feels like" temperature—the heat index—routinely cruises past $105^{\circ}F$. Basically, if you step outside at 2:00 PM in July, you aren't just walking; you’re swimming through hot soup.
August is the king of this. It’s the hottest month, and the nights don't offer much relief, usually bottoming out at $72^{\circ}F$. If you’re planning a trip to Lake Cypress Springs during this time, you’ve got the right idea. The water is the only place you'll want to be.
Why the "Comfortable" Months are a Moving Target
Most travel sites will tell you to visit in the spring or fall. They aren't wrong, but they are vague.
October is, quite frankly, the best-kept secret of mt vernon tx weather. It’s the clearest month of the year. The sky is clear or mostly clear about 70% of the time. You get these crisp mornings in the 50s and afternoons in the high 70s. It’s perfect for the Harvest Festival.
Spring is a different beast. March and April are beautiful, sure. The bluebonnets and crimson clover start popping up along the highways. But spring is also when the atmosphere gets a little "twitchy."
- The Storm Factor: Mount Vernon sits in a region where cool air from the north slams into that warm, moist Gulf air.
- Rainfall Spikes: May is actually the wettest month of the year, averaging about 5 inches of rain.
- Tornado Season: While Mount Vernon doesn't see the frequency of "Tornado Alley" out west, North East Texas gets its fair share of severe thunderstorms and the occasional twister.
The Winter "Wet-Cold"
Winter here is short—late November to late February—but it's weirdly biting. The average low in January is $34^{\circ}F$. On paper, that’s not bad. But because the air is so damp, $34^{\circ}F$ in Mount Vernon feels significantly colder than $20^{\circ}F$ in a dry climate like Denver.
Snow is a rarity. You might see an inch or two over the course of the whole year. What you really have to watch for is "cobblestone ice" or freezing rain. Every few years, an Arctic blast settles in, and because our infrastructure isn't built for a deep freeze, things can get tricky. Just look at the historical data from January 2025 or the "Big Freeze" of 2021; when it hits, it hits hard.
Local Survival Tips
If you're living here or just passing through, there are a few things you basically have to accept about the local climate.
- Humidity is the boss. Check the dew point, not just the temperature. If the dew point is over 65, you’re going to be sticky.
- The "Second Summer." Don't be fooled by a cold snap in early September. We almost always get a "Second Summer" where temps spike back into the 90s for a week before fall actually sticks.
- Layering isn't a suggestion. In November, you can start the day in a heavy coat ($38^{\circ}F$) and end it in a t-shirt ($70^{\circ}F$). Keep a hoodie in the truck.
Actionable Weather Prep
If you are planning an event or a move, don't rely on the "monthly average" charts. They smooth out the peaks and valleys that actually define mt vernon tx weather. Instead, use a "perceived temperature" tool or a dew point tracker.
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For outdoor projects, aim for the "Clearer" window between June 1 and November 13. While it’s hot, it’s also the time when you’re least likely to have a week-long washout. If you’re coming for the scenery, the third week of September into mid-October is your goldmine. You get the benefit of the clearing skies without the $100^{\circ}F$ August punch.
Monitor the National Weather Service out of Shreveport (SHV), as they handle the specific NEXRAD coverage for Franklin County. Local conditions can change fast, and they are usually the first to flag the "dry line" storms that occasionally roll through from the west.
Check your AC filters in April. Seriously. By May, the system will be running 12 hours a day, and by July, it won't stop. Making sure your insulation is tight and your coolant levels are checked before the June humidity spike will save you a massive headache—and a huge electric bill.