Our lawn had gone from beautiful to being overrun with weeds. Since the drought in California has continued for so long we just basically gave up and now all grass and weeds are dead. Yup, we have a large dirt yard.
I'm hoping for an end to the drought this winter and if so, I may reseed the backyard.
If the seeds don't sprout the weeds were not worthy to be called weeds. So they will probably sprout, yes. Many weed seeds can go decades and still sprout...it's part of how they get to be weeds.
Both traditional and chemical methods would let the weeds sprout (without grass seed) and then kill them, just by different methods. After a few rounds of that you'd start with the grass seed.
In your shoes I'd be considering alternate yard treatments that don't depend on the drought ending (and erosion control if it ends with heavy rains)
If by "reseed" you mean that you're planting grass, I'd suggest a different alternative: not grass. Weeds aren't your biggest enemy here: drought is. Though perhaps less extreme than @Wayfaring's mulch or rocks, there are a number of alternatives that are more drought-resistant.
Consider a drought-resistant thyme or clover, as suggested in this grass-alternative lawn article. Similar alternatives and additional description in this article. The latter also includes my personal recommendation: artificial turf.
No lawn-like plant is going to tolerate no water, especially not one that has any durability for foot traffic. Artificial turf is very attractive: minimal maintenance, water capture possibilities, durable, permanent, and reasonably good looking, also.
I can't immediately find a video of the episode, Ask This Old House did an episode on a Las Vegas backyard lawn replacement that was pretty elegant. More description at Episode #1304 of Season 13 of ATOH.
If the lawn is full of weeds, need to see a picture, I'd rent a sod cutter and cut the sod out, turn it upside down to beef up your new and LARGER plant beds. Make a much smaller yet well defined lawn using unbroken radius (keep the radius of any curves contant until changing the direction. can use any radius but keep constant and clean edges with a flat edge shovel throwing all debris on new plant beds). Grade well, use a rolling drum to compact, good organic slow release fertilizer and water well for 11 days or whenever you can grab a hunk of sod, pull up and it stays put. Use a mechanical spreader, never hand throw. If seeding use a mechanical spreader as well and water LIGHTLY 4-5X per day to keep the surface moist.
Mow your lawn NO SHORTER THAN 3". This will conserve water and discourage weed seeds from sprouting. Also makes a healthier grass plant to have enough top growth to feed the roots and be vigorous enough to outcompete any weed. Watering practices after your lawn is established is CRITICAL. WATER DEEPLY and allow to dry out before watering again. The best way to know is when you walk across the lawn you leave footprints as the blades of grass won't pop back up. This is the sign to water again and water deeply...at least 4-6" deep! In a few months you will only be watering 1" per week, have healthy, drought tolerant dark green grass. This gets the plant to develop a deeper root system and become drought tolerant as your grass can get at the moisture deeper into the soil. Shallow rooted grasses are the first to go in a drought. Watering a little every day causes shallow root systems. So always water deeply and allow to dry before watering again! Fertilize at least 3X per season with SLOW RELEASE as this is slower, less stressful to the grass and mow with SHARP blades a minimum of once per week. Growth slows when the blades are 3". You'll be taking off less. Aerate with an aerator that pulls plugs of grass and soil out of your lawn and leave the plugs where they lie. Once per year minimum.
