The ability to swiftly and efficiently assess information is essential for a successful response in the case of a natural disaster, such as wildfires. Access to accurate and timely information is critical for first responders and the public to make informed decisions within tight timelines. Although traditional sources of information such as satellite images, field surveys, and contact centers are costly and time consuming, social media content is more affordable and immediately available, making it a useful tool for real-time updates. However, extracting insights from the abundance of user-generated content on social media can be challenging. Machine learning can automatically categorize posts, filter noise and highlight crucial information for responders and the public. In this work, we introduce, WildFireCan-MMD, a new multimodal dataset tailored to Canadian wildfires, collected from user-generated posts on X during the 2022, 2023, and 2024 British Columbia and Alberta wildfires. We applied topic clustering followed by manual annotation to label this dataset into thirteen wildfire-relevant themes. We tested two Generative Large Vision-Language Models (GLVLMs), namely, gpt-4o-mini and open-source LLaVA, for the classification of WildFireCan-MMD in zero-shot setting. We also developed custom classifiers, including RoBERTa and ViT transformer combinations with early and late fusion. Our results show that if no training data is available, gpt-4o-mini might serve as a practical zero-shot classifier. However, with labeled training data, even a basic Gaussian Naive Bayes classifier outperforms gpt-4o-mini. Fine-tuned transformers outperform gpt-4o-mini by a large margin of 23%. This study underscores the value of curated, task-specific datasets and training customized classifiers despite recent advancements in zero-shot GLVLMs.