Is it okay to water your babies on a hot day? (outdoor grow)

Is it ok to water your plant on a hot day? (25+ Degrees Celsius)

Also does anyone have any idea whats wrong with my baby?
Sorry for the bad quality pics, all I have at the moment.

Its outside from sunrise to sunset 6.30am - 8.30pm and then its under a flourosent light globe in my closet for another 4 hours so it has 18/6. Its about 3 weeks old.

any help would be awesome.

Peace

Soil-Premium Potting mix (with compost, I'm not 100% sure my friend mixed it for me)
Lighting - day, sun night, floursent light globe an inch away
Watering - Give it a good watering when the soil is dry 6 cm under the soil.
If theres anything else you need to know just ask

I don't want to make you overwater, but I think you may not be moistening the soil enough when you water. The coyteldon/starter leaves are already yellowing and your plant is still pretty small. I would assume its not pulling enough nutrients out of the soil.
Remember, your watering the soil to get the micronutrients and bacteria growing so the plant can absorb what it needs along with water and oxygen.

Your probably right, the last time I tried to grow I overwatered and killed them so I'm very cautious when I water now, but I don't think I'm severely underwatering them.

How long have you been putting it out in full sun? A lot of times if you don't ease a plant into the sun by placing it in the shade for the first week or so this will happen. A kinda shock happens and the plant quits absorbing nutrients properly. It's basically sick from too much sun all at once.
But it also looks like it could use a good watering like the other poster said. My prediction is this: start watering more regularly and it will eventually (1.5-2weeks) get used to the sun exposure shed those dying leaves and start looking better for ya (as far as leaves yellowing/dying).

I've been putting it in full Sun for like 2 weeks out of the 3 weeks its been alive. Should I just give it a good water before a hot day (22-25DegreesCelcius+)?

^Yes, it's best to water in the morning, then let the plant process all day long, in the direct sunlight. The thing to try and avoid, is spraying the foliage, during intense sunlight, because it is claimed that special circumstances can create burns, due to the magnification effect of the water droplets. At any rate, it's always okay to water your soil, no matter how hot the day will become. Actually, it's the best time, IMO.

you want some perlite in that soil dude