Here's a calculation I like to use using Temperature + Dew Point:
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For example, if the Temp (70) + Dew Point (60) is combined (130), then I check the chart for an adjustment of pace. So a T+D of 130 suggests a 2% adjustment. So if HM Tempo was 9:48, then consider aiming for 9:59 pace instead. It's a starting point calculation and everyone reacts differently, but it's a good place to check in on prior to a run/race. You can see how a 9:48 pace at T+D 100 (or HM Tempo) will probably feel more like 10 miler pace at a T+D of 130. So that 30 point differential means that pace is now meant for a 3.11 mile lesser distance on a likely perception of effort basis.
When coming from a colder climate to a warmer climate, one thing you can consider for future races is heat acclimation training. Overdressing in cold conditions to force a micro-climate close to your body that simulates heat/humidity. So for instance, if the temp outside is 30F, then I dress like it's 0-10F instead. Wearing a poorly circulating jacket. This will force adaptations in your body to help prepare for running in the warmer conditions on race day (sweat rate, thinning out of blood, increased plasma blood volume). Keep in mind that you'll be sweating a ton, so make sure to drink plenty of liquids during this type of run, and make sure you're mindful of cutting cool-downs short to prevent getting super cold from the sweat and lesser pace. It takes about 10-14 days to notice the effects of heat acclimation training.
Training in the cold, but racing in the heat: The need for heat acclimation
Humidity vs Temp (and Sunshine): What time of day should I run?
The other point is, that you trained for a half marathon and completed it. Those who do Dopey, train for Dopey and can complete it. So you may be sore today, and think how can I possibly? But if you put in the prerequisite training, then I certainly believe you can do it regardless of how sore you may feel today.