FWIW I think spring is the perfect time of year to have a baby. In the first 6 months, which is the toughest time IME/IMO, you get mostly good weather and sunshine to motivate you to leave the house (even if it's just for a short walk). It's also handy for drying all the laundry 
And, a longer term consideration, I think it's good for the child to have a birthday halfway through the academic year, so they're not the oldest or the youngest, and they're 4.5 when they start which is good timing for most children.
DC1 was born in March, DC2 was born in September. I was/am less happy about September, firstly because I was heavily pregnant over the summer which was NOT pleasant, secondly it was winter when she was 3-5 months old which is a really tough stage (or it was for me anyway), I struggled massively with my mental health during that time. Thirdly, I do worry that she will be nearly 5 when she starts school, one of the oldest, and might get bored by 2 years in preschool... not the end of the world though and most teachers say it's an advantage to have a September birthday.
On a practical note, all the season-specific baby clothes I'd saved were completely the wrong size
for example, for DC1 I had summer clothes in 3-6 months and 12-18 months, but for DC2 I needed winter clothes in those sizes and summer clothes in 9-12 and 18-24 months. Still, nice excuse to buy some new bits 