I also live in VA and am experiencing similar temperature fluctuations. My chicks went outside at about 4.5 weeks old without a heat lamp. Daytime temps were 90+ and nighttime temps were around 60. They are in a pen that has a roof but only wire for walls (a temporary situation while I finish the coop). On very hot days, I have been putting a frozen water bottle in their water to keep it cool and I check on them frequently. They have been just fine with no signs of illness or distress. I have RIRs and Delawares and I have come to the determination that chicks aren't all that fragile. They are now approaching 6 weeks old and last night the temps dropped into the 50s. They did just fine with no signs of distress.
Consider also that several areas have large numbers of feral chickens. Most are warmer locations such as Florida and Hawaii, but even they experience temperatures in the 50s and below for at least part of the year, but this doesn't have any significant impact on the feral chicken populations. I wouldn't expose itty bitty fuzzbutts to these temps, but after 4 weeks, I think they are pretty hardy in all but the more extreme temperatures.
Consider also that several areas have large numbers of feral chickens. Most are warmer locations such as Florida and Hawaii, but even they experience temperatures in the 50s and below for at least part of the year, but this doesn't have any significant impact on the feral chicken populations. I wouldn't expose itty bitty fuzzbutts to these temps, but after 4 weeks, I think they are pretty hardy in all but the more extreme temperatures.
