Is second week in April too hot for Seville?

April shouldn’t be bad. You can check online for last year’s average for the month. The average high is 72. Last year it was warmer than usual.

Seville in April is very pleasant and enjoyable, temps are solidly in the 70's during the day and low 50's to high 40's in the evening. This is why April/May is arguably the most favorable weather-wise to visit. late-May thru early-Oct is when temps go well past the 80's. You will not have any issues with heat in April, the locals are still wearing their pants and sweaters then.

Spring-time rain showers throughout Spain are not uncommon, be prepared with an umbrella or, a light rain shell, good opportunity to plan a museum day or, just enjoy the short downpour in a cafe. I've visited Madrid and Barcelona in April and rain was not an issue.

We went to Spain April 1-April 9, 2019 . We landed in Madrid with rain that was sideways and saw snow flakes that melted before they landed. It was bone chilling! We did take the HOHO bus and sat on top letting the rain slap us--we are defiant folks. Seville was our next stop with decent weather in the 40s without rain. Granada, again, was sideways rain that never let up. Our last stop was Barcelona without rain and mid-50s.
January 2023 we again were in Spain with reverse order visits (Barcelona, Granada, Seville, Madrid). The weather was delightful with no rain and @ 60 and warmer in Barcelona. Go figure.

I've found timeanddate.com to be extremely helpful and accurate for planning trips. You never know when a heatwave or cold snap might occur, though. For example, we were in Paris last September for their hottest weather on record for Sept. It was 95 or 96 for over a week.

I hope you have a wonderful time no matter the weather. Spain is one of my favorite countries!

I suppose it can get into the 80's or 90's in April (especially as weather trends change), but not regularly, and you get a nice cool down at night, so it is not like 80's and 90's in August. April is a relative dry month, if it does rain, it likely will be short duration, spotty, not constant rain for days.

As hinted by the range of responses above, weather varies quite a lot from year to year, especially during shoulder seasons. I'd have said "Pleasant; not a problem" based on my 2019 experience of April in Andalucia if I hadn't followed jaimeelsabio's link to the very useful Timeanddate.com website. As you can see, April was brutal last year. A lot of days were unpleasantly hot that month. It can happen. Be sure your lodgings are air conditioned so you can escape there for a break in the middle of the day if you need to. Take into consideration that doing so will not be an option if you've day tripped away from your base city.

I like to look at the actual, historical, day-by-day weather statistics on timeanddate.com for the last five years when I'm planning a trip to a potentially problematic location. Just use the pull-down box above the graph, at the far right, to change the month and year displayed. Use the Search box near the upper right to change the location.

I remember leaving Sevilla on April 2, 2011, and the temperature was around 32 degrees C (about 90 degrees F).
In Granada, one week earlier, it was a very pleasant 25 degrees C (77F).