Predicting My 5K Race Time

In just less than one week, on August 6 in the evening, I'll run my first 5K race in about 2 years. I think I've run only 2-3 5Ks in the last 5 years. Just not my race distance. I consider myself an ultrarunner, not a speed demon. But as I've grown older, I've become a bit fascinated (and concerned) with speed. I've lost it! I've tried to incorporate speed work into my weekly training the last 4 weeks. Nothing extreme, but a little tempo here, intervals there, and strides when I remember. So, now I need to figure out how to pace myself next week for this 5K race. 

What is my predicted race finish time? I have several sources of information to guide me. But they do not agree with each other! Here are examples:

• Garmin predicts: 21:43
• Stryd predicts: 22:58
• Runalyze predicts: 24:47
• My recent 5K time trial on the race course: 22:47

So, what is an old ultrarunner to do? These predictions cover a wide range of finish times from 24:47 to 21:43. I normally run easy on trails so I think the estimates are on the slow side. Since I ran the course in a time of 22:47 a little over a week ago, I think I can do that again. I was pushing hard, but it was not a race, so maybe I can slightly improve on that effort. Garmin prediction might be the best: 21:43. Can I actually improve by a full minute? I think so. The race starts at 6:30pm which is very different than my usual early morning runs (and time trial). It will be warmer, but maybe less humid. I don't enjoy the heat, but I have been running in warm/hot and humid conditions for weeks. I can suffer for 20 minutes, right? 21 minutes? 22? We shall see! Wish me well and I'll report back in a week. 

UPDATE: I finished in 23:30. Disappointing. Warm and humid weather hurt me.