For two weeks I cannot refill my humidifier. What are my chances my plants will still be okay when I get back?

Forgot to tsay -- those 2 pics are 42 days from sprout. You can see how much larger the ones that didn't have a shit-ass climate grew. There are 3-4 strainsn and 8 plants, so it's not just "1" plant. it's clearly impacting them all in similar ways.

45% won't be too bad as long as temperature isn't too high. I can't tell you the exact VPD that will stall out a plant, but it does happen and it is a real concern. Maybe a week at 1.8-2.0 (atmospheric temp, falsely calculated because that's my familiarity -- VPD is technically calculated from leaf surface temp and RH, that requires numerous measurements with an infrared themometer and averaged out) If you go much over 73-75F, might run into issues after a couple weeks. It won't kill a plant. you fix the climate and within a few days it'll kick back into gear. Anecdote: https://ibb.co/BVqGhdC1 https://ibb.co/xSPgXVnK These are 2 grows at 42 days. The smaller batch of plants had a humidifier go down for 7-10 days. It severely impacted my expected and familiar growth rate. This was probably much worse than what will result from "45%" RH. I'd wager it was around 30-35% and 73-75F give or take.. I didn't look up the notes but that's the typical temperature at that stage with lights at vege power level. this stuff doesn't always happen overnight.. it may take weeks to cause something you can notice. the more severe and above an ucertain threshold (but might be able to find that reference info), the faster it'll have a negative repercussion.

They will be 100% ok, don't stress. Cannabis has survived forever without human interference...........it is a robust pamt, not a dainty fern that needs "princess perfect" conditions to survive.

Depends on the growth stage. Flowering they will like it. Shoots and seedlings will not like 45% relative humidity. Adult plants in vegetative stage will tolerate it well for some days as you get working toward solving the problem. 50% humidity for any adult plant flowering or not is completely ok.

Your plants will be fine. I always think, there is a tight range of ideal conditions that we aim for and then there is a wide window of OK conditions. They will draw up more water with that humidity so make sure they are well watered.

Your water consumption is two fold, the air and the medium. Your air is driven primarily by the lung room conditions, turnover rate, and then your plant needs. Your plant is driven by light, nutrients, and co2/o2..... Accordingly, you can impact both of those by adjusting your lung room turnover and light intensity in 5 secs on the way out of the door.

Dont worry. They will be fine. They just need water to compensate for it. You have now a dry warm climate - which is not bad for this kind of plants ;). Some genetics even like it more this way. (You can try to lower your temp a bit - so your VPD gets better. Maybe dimm the light 10% down or hang it a bit higher. but 45% is not really a problem as long they have enough water.)